AMS Certified Broadcast Meteorologist (CBM) — Questions and Answers

Question 1: The 850 hPa temperature field is commonly used to diagnose what in winter forecasting?

Stratospheric intrusions
Tropopause height
Jet stream position
Precipitation type (rain vs. snow boundary) (Correct answer)

Correct answer: Precipitation type (rain vs. snow boundary)

The 850 hPa (~1500 m) temperature is used to distinguish rain/snow boundaries, with approximately 0°C as a key threshold.

Question 2: Which parameter best describes the potential for long-track tornadoes in supercells?

Total Totals Index
Significant Tornado Parameter (STP) (Correct answer)
CAPE alone
K-Index

Correct answer: Significant Tornado Parameter (STP)

The Significant Tornado Parameter (STP) combines CAPE, LCL height, SRH, and shear to identify environments favorable for significant (EF2+) tornadoes.

Question 3: What is wind shear's primary role in supercell thunderstorm formation?

It weakens the updraft over time
It produces precipitation immediately
It tilts the updraft, separating it from the downdraft and allowing rotation (Correct answer)
It reduces moisture convergence

Correct answer: It tilts the updraft, separating it from the downdraft and allowing rotation

Wind shear tilts the updraft away from the downdraft, preventing the storm from choking itself and promoting sustained, rotating convection.

Question 4: What is the primary meteorological use of the GOES-R Advanced Baseline Imager (ABI)?

Multi-band visible, near-IR, and IR imaging for cloud, moisture, and fire detection (Correct answer)
Radar-like precipitation mapping
GPS-based sounding
Upper-air temperature only

Correct answer: Multi-band visible, near-IR, and IR imaging for cloud, moisture, and fire detection

The ABI on GOES-R provides 16-band imagery from visible to thermal infrared for monitoring clouds, moisture, severe storms, fires, and other phenomena.

Question 5: What is Q-vector divergence used to diagnose in synoptic meteorology?

Vertical motion without computing vorticity separately (Correct answer)
Surface wind direction
Tropopause folding events
Tropical cyclone track

Correct answer: Vertical motion without computing vorticity separately

Q-vector divergence provides a direct measure of synoptic-scale vertical motion without separating vorticity and thermal advection terms.

Question 6: IPCC Shared Socioeconomic Pathways (SSPs) are used in climate projections to represent:

Different assumptions about future greenhouse gas emissions and societal development trajectories (Correct answer)
Projections of sea level rise under different ocean warming scenarios
Varied assumptions about aerosol concentrations in future climate models
Alternative global temperature targets set by international agreements

Correct answer: Different assumptions about future greenhouse gas emissions and societal development trajectories

SSPs describe plausible alternative futures combining different mitigation challenges and socioeconomic conditions, ranging from SSP1-1.9 (very low emissions) to SSP5-8.5 (very high emissions) to bracket the range of possible futures.

Question 7: What radar feature indicates a strong rotating updraft in a supercell?

Mesocyclone signature (Doppler couplet) (Correct answer)
Bright band
BWER (Bounded Weak Echo Region)
Bow echo

Correct answer: Mesocyclone signature (Doppler couplet)

A mesocyclone signature on Doppler radar shows a couplet of approaching and receding velocities indicating rotation in a thunderstorm updraft.

Question 8: A zonal flow pattern in the mid-latitudes is characterized by what?

Frequent cutoff lows
Predominantly west-to-east flow with weak amplitude (Correct answer)
Strong meridional (north-south) wind components
Strong blocking patterns

Correct answer: Predominantly west-to-east flow with weak amplitude

Zonal flow features nearly west-to-east jet stream with weak ridges and troughs, typically associated with milder, less extreme weather.

Question 9: What is the Madden-Julian Oscillation (MJO) and how does it affect US weather?

The seasonal shift of the ITCZ
A semi-annual ocean oscillation affecting Pacific SSTs
A high-frequency atmospheric wave affecting daily forecasts
An eastward-propagating pattern of enhanced and suppressed tropical convection on 30–90 day timescales that modulates global weather (Correct answer)

Correct answer: An eastward-propagating pattern of enhanced and suppressed tropical convection on 30–90 day timescales that modulates global weather

The MJO is an intraseasonal oscillation that modulates tropical rainfall and teleconnects to affect precipitation patterns, temperatures, and severe weather across the US.

Question 10: A positive phase of the North Atlantic Oscillation (NAO) is associated with:

Stronger westerlies and warmer, wetter winters over northwestern Europe (Correct answer)
Weaker westerlies and cold, dry winters over northwestern Europe
Increased blocking events over the North Atlantic
Stronger trade winds in the tropical Atlantic

Correct answer: Stronger westerlies and warmer, wetter winters over northwestern Europe

A positive NAO features an enhanced pressure gradient between the Azores High and Icelandic Low, driving stronger westerlies that bring mild, wet conditions to northwestern Europe and northern Eurasia.

Question 11: What does ensemble forecasting provide compared to a single deterministic model run?

Faster computation time
Probabilistic forecast information by running multiple model simulations with varied initial conditions (Correct answer)
A single best-estimate forecast
Higher spatial resolution

Correct answer: Probabilistic forecast information by running multiple model simulations with varied initial conditions

Ensemble forecasting produces a range of possible outcomes by perturbing initial conditions and model physics, quantifying forecast uncertainty.

Question 12: What is the Saffir-Simpson Hurricane Wind Scale used to classify?

Hurricane intensity by maximum sustained wind speed (Categories 1–5) (Correct answer)
Storm surge height
Tropical storm intensity by central pressure
Overall storm destructive potential including rainfall

Correct answer: Hurricane intensity by maximum sustained wind speed (Categories 1–5)

The Saffir-Simpson scale classifies hurricane intensity into five categories based solely on maximum sustained wind speed.

Question 13: What does PVU (potential vorticity unit) measure?

Precipitation rate
Wind gust factor
Surface pressure anomaly
Isentropic potential vorticity (Correct answer)

Correct answer: Isentropic potential vorticity

A PVU (10⁻⁶ K·m²·kg⁻¹·s⁻¹) is the standard unit for potential vorticity on isentropic surfaces.

Question 14: A Rex block pattern in the upper atmosphere consists of what configuration?

An omega block at 500 hPa
A split jet stream with equal branches
A high to the north with a low to the south blocking zonal flow (Correct answer)
Two troughs of equal amplitude

Correct answer: A high to the north with a low to the south blocking zonal flow

A Rex block features an upper-level high poleward of an upper-level low, interrupting the zonal (west-to-east) flow.

Question 15: What does a negatively tilted trough indicate on upper-level charts?

Weakening system and subsidence
Amplifying system and enhanced severe weather potential (Correct answer)
Tropical moisture surge
High-pressure building

Correct answer: Amplifying system and enhanced severe weather potential

A negatively tilted trough (tilting SW to NE) indicates an amplifying system with increased cyclogenesis and severe weather potential.

Question 16: What is a derecho?

A type of cold front
A widespread, long-lived wind storm produced by a fast-moving convective system (Correct answer)
A tropical squall system
A severe thunderstorm limited to one county

Correct answer: A widespread, long-lived wind storm produced by a fast-moving convective system

A derecho is a widespread, damaging straight-line wind event produced by a fast-moving convective system extending at least 400 km.

Question 17: What causes the hook echo feature on radar associated with supercell thunderstorms?

An outflow boundary intersecting a squall line
Heavy rain wrapping around a low-pressure center
Hail core wrapping around a clear air region
Rotation in the storm drawing precipitation around the mesocyclone (Correct answer)

Correct answer: Rotation in the storm drawing precipitation around the mesocyclone

The hook echo forms when the supercell's rotating updraft wraps precipitation around the mesocyclone, creating the distinctive hook shape.

Question 18: The hydrostatic equation relates pressure change to which atmospheric quantity?

Air density and gravity (Correct answer)
Temperature gradient
Relative humidity
Wind speed

Correct answer: Air density and gravity

The hydrostatic equation states that the pressure decrease with height equals air density times gravitational acceleration.

Question 19: What is the Global Forecast System (GFS) and who operates it?

A European global NWP model operated by ECMWF
A global NWP model operated by NOAA/NWS for weather prediction out to 16 days (Correct answer)
A seasonal forecast model operated by NASA
A high-resolution US regional model

Correct answer: A global NWP model operated by NOAA/NWS for weather prediction out to 16 days

The GFS is NOAA's operational global NWP model, producing forecast guidance out to 16 days at ~13 km horizontal resolution.

Question 20: CAPE (Convective Available Potential Energy) is measured in which units?

Meters per second
Kelvin
Pascals
Joules per kilogram (J/kg) (Correct answer)

Correct answer: Joules per kilogram (J/kg)

CAPE is expressed in J/kg and represents the positive buoyant energy available to a rising parcel of air.

Question 21: What is the primary driving mechanism for the jet stream?

Surface friction
Horizontal temperature gradients in the troposphere (Correct answer)
Ocean currents
Stratospheric ozone heating

Correct answer: Horizontal temperature gradients in the troposphere

The jet stream is driven by strong horizontal temperature gradients, particularly between polar and tropical air masses.

Question 22: Which flow regime is characterized by a small Rossby number and quasi-geostrophic balance?

Microscale turbulence
Synoptic-scale flow (Correct answer)
Sea breezes
Thunderstorm updrafts

Correct answer: Synoptic-scale flow

Synoptic-scale systems have small Rossby numbers, making quasi-geostrophic balance a good approximation.

Question 23: A SIGMET (Significant Meteorological Information) advises pilots of what?

Routine weather along a route
Hazardous meteorological conditions affecting aircraft safety (severe turbulence, icing, volcanic ash) (Correct answer)
Surface wind forecasts at airports
Precipitation probability along a route

Correct answer: Hazardous meteorological conditions affecting aircraft safety (severe turbulence, icing, volcanic ash)

SIGMETs are urgent weather advisories warning pilots of non-convective hazards including severe turbulence, severe icing, volcanic ash, and tropical cyclones.

Question 24: Mountain waves and associated turbulence are detected most effectively with which tool?

Pilot Reports (PIREPs) and upper-air wind analysis (Correct answer)
Lightning detection networks
Radiosonde humidity profiles
Surface METAR observations

Correct answer: Pilot Reports (PIREPs) and upper-air wind analysis

PIREPs from aircraft combined with upper-air wind profiles are essential for identifying and forecasting mountain wave turbulence.

Question 25: What is the Lorenz predictability limit for atmospheric forecasting?

Approximately 2 weeks (Correct answer)
30 days
24 hours
6 hours

Correct answer: Approximately 2 weeks

Edward Lorenz showed that due to chaotic atmospheric dynamics, deterministic weather forecasts lose skill beyond approximately two weeks.

Question 26: Which layer in the atmosphere separates the troposphere from the stratosphere?

Mesopause
Stratopause
Tropopause (Correct answer)
Thermopause

Correct answer: Tropopause

The tropopause is the boundary where temperature stops decreasing with height and marks the top of the troposphere.

Question 27: The Brunt-Väisälä frequency measures what atmospheric property?

Frequency of thunderstorm occurrence
Convection initiation frequency
Frequency of pressure waves at the surface
Buoyancy oscillation frequency of a displaced air parcel in a stable layer (Correct answer)

Correct answer: Buoyancy oscillation frequency of a displaced air parcel in a stable layer

The Brunt-Väisälä (or buoyancy) frequency describes how fast a displaced parcel oscillates vertically in a stably stratified atmosphere.

Question 28: What is quantitative precipitation estimation (QPE) from radar?

Estimation of rainfall rates and totals from radar reflectivity using Z-R relationships (Correct answer)
A forecast method for 24-hour precipitation
A qualitative description of storm intensity
Flood stage prediction

Correct answer: Estimation of rainfall rates and totals from radar reflectivity using Z-R relationships

QPE uses Z-R relationships (reflectivity to rain rate) to convert radar reflectivity values into estimates of actual precipitation amounts.

Question 29: The Polar Front Jet Stream typically forms near which atmospheric boundary?

The trade wind inversion
The subtropical high belt
The equatorial convergence zone
The boundary between polar and mid-latitude air masses (Correct answer)

Correct answer: The boundary between polar and mid-latitude air masses

The polar front jet stream develops along the sharp temperature gradient between cold polar and warmer mid-latitude air masses.

Question 30: What is the significance of the wet-bulb potential temperature in air mass analysis?

It indicates wind direction along fronts
It measures precipitation efficiency
It is conserved in both dry and moist adiabatic processes, identifying airmass origins (Correct answer)
It diagnoses upper-level troughs

Correct answer: It is conserved in both dry and moist adiabatic processes, identifying airmass origins

Wet-bulb potential temperature is conserved through both dry and saturated adiabatic processes, making it an excellent tracer of air mass identity.

Question 31: A bow echo on Doppler radar is associated with what type of hazard?

Tornado family outbreak
Damaging straight-line winds and bookend vortices (Correct answer)
Flash flooding only
Extreme hail

Correct answer: Damaging straight-line winds and bookend vortices

Bow echoes are bow-shaped radar reflectivity features associated with strong rear-inflow jets and damaging straight-line winds.

Question 32: What atmospheric quantity does a rawinsonde measure in addition to temperature and humidity?

Precipitation rate
Cloud base height
Wind speed and direction throughout the vertical profile (Correct answer)
Solar radiation

Correct answer: Wind speed and direction throughout the vertical profile

A rawinsonde is a radiosonde tracked by GPS or radar to also provide a complete vertical wind profile through the atmosphere.

Question 33: What does the term 'forecast bust' mean in operational meteorology?

A forecast that verifies perfectly
A high-confidence ensemble forecast
An overwarned event
A significant failure of a forecast, where the predicted weather did not materialize as expected (Correct answer)

Correct answer: A significant failure of a forecast, where the predicted weather did not materialize as expected

A forecast bust occurs when the issued forecast significantly diverges from actual conditions, representing a major forecaster or model failure.

Question 34: What advantage do LEO (Low Earth Orbit) satellites have over GEO satellites for atmospheric sounding?

Longer operational lifetime
Higher spatial resolution and better coverage of polar regions (Correct answer)
Faster data delivery to forecasters
Continuous coverage of one location

Correct answer: Higher spatial resolution and better coverage of polar regions

LEO satellites provide higher spatial resolution and full global coverage including polar regions, though with less frequent revisit times than GEO satellites.

Question 35: 500 hPa height charts are used primarily to analyze what?

Mid-tropospheric steering flow and troughs/ridges (Correct answer)
Precipitation type
Boundary layer humidity
Surface wind patterns

Correct answer: Mid-tropospheric steering flow and troughs/ridges

500 hPa charts depict mid-tropospheric flow, showing troughs, ridges, and the steering layer for weather systems.

Question 36: The Pacific Decadal Oscillation (PDO) differs from ENSO primarily in that:

The PDO operates on decadal timescales, while ENSO operates on 2–7 year timescales (Correct answer)
The PDO affects only the North Pacific, while ENSO affects the whole globe
The PDO is driven by atmospheric forcing, while ENSO is purely oceanic
The PDO only affects SSTs, while ENSO affects winds and precipitation

Correct answer: The PDO operates on decadal timescales, while ENSO operates on 2–7 year timescales

The PDO is a long-lived pattern of Pacific SST variability with phases lasting 20–30 years, much longer than ENSO's 2–7 year cycle, and modulates ENSO's impacts on North America.

Question 37: Atmospheric Emitted Radiance Interferometer (AERI) instruments are used at ground level to retrieve what?

Wind direction
Cloud albedo
Surface precipitation
Continuous high-temporal-resolution temperature and moisture profiles in the boundary layer (Correct answer)

Correct answer: Continuous high-temporal-resolution temperature and moisture profiles in the boundary layer

AERI instruments measure downwelling infrared radiance to retrieve temperature and water vapor profiles in the lower atmosphere at high temporal resolution.

Question 38: Ground-based microwave radiometers in meteorology are used primarily for what purpose?

Profiling temperature and humidity through the lower troposphere continuously (Correct answer)
Detecting lightning
Surface wind measurements
Measuring snow depth

Correct answer: Profiling temperature and humidity through the lower troposphere continuously

Microwave radiometers passively detect thermal emissions from atmospheric oxygen and water vapor to retrieve continuous temperature and humidity profiles.

Question 39: The standard climatological reference period used by the World Meteorological Organization (WMO) to define climate normals is:

30 years (Correct answer)
20 years
10 years
50 years

Correct answer: 30 years

WMO defines climate normals as 30-year averages (currently 1991–2020) to provide a stable statistical baseline that smooths interannual variability.

Question 40: What is the Rossby number used to measure?

Relative importance of rotation vs. inertia in atmospheric flow (Correct answer)
Humidity ratio
Vertical wind shear
Rainfall intensity

Correct answer: Relative importance of rotation vs. inertia in atmospheric flow

The Rossby number compares inertial forces to Coriolis forces, indicating when rotation becomes dynamically important.

Question 41: What is the Lifted Index (LI) used to assess?

Upper-level wind speed
Atmospheric stability and convective potential (Correct answer)
Soil moisture availability
Fog formation likelihood

Correct answer: Atmospheric stability and convective potential

The Lifted Index measures stability by comparing the temperature of a lifted parcel to the environment at 500 hPa; negative values indicate instability.

Question 42: What is a heat burst in mesoscale meteorology?

Sensible heat release from land after sunset
Extreme daytime heating over deserts
A warm frontal passage
Sudden warming and wind gusts at the surface caused by a precipitating downdraft descending into dry air (Correct answer)

Correct answer: Sudden warming and wind gusts at the surface caused by a precipitating downdraft descending into dry air

A heat burst occurs when a downdraft from a dying thunderstorm descends and dries adiabatically, causing sudden surface temperature spikes and gusty winds.

Question 43: What is the primary source of energy for extratropical cyclones?

Shortwave radiation
Baroclinic instability from horizontal temperature gradients (Correct answer)
Sensible heat from the ocean surface
Latent heat release

Correct answer: Baroclinic instability from horizontal temperature gradients

Extratropical cyclones derive their energy primarily from baroclinic instability, converting available potential energy from horizontal temperature contrasts.

Question 44: Which equation describes the conservation of mass in atmospheric dynamics?

Thermodynamic energy equation
Navier-Stokes equation
Hydrostatic equation
Continuity equation (Correct answer)

Correct answer: Continuity equation

The continuity equation ensures that mass is neither created nor destroyed within an air volume.

Question 45: What is the Probability of Precipitation (PoP) in a weather forecast?

The probability that at least 0.01 inches of precipitation will occur at any given point in the forecast area (Correct answer)
The confidence level of the forecast model
The percentage of the forecast area that will receive rain
The expected rainfall amount at a point

Correct answer: The probability that at least 0.01 inches of precipitation will occur at any given point in the forecast area

PoP represents the probability that a specific point will receive measurable precipitation (≥0.01 inch) during the forecast period.

Question 46: What stability index combines wind shear and instability to assess severe weather potential?

K-Index
Storm Relative Helicity (SRH) (Correct answer)
Totals-Totals Index
Showalter Index

Correct answer: Storm Relative Helicity (SRH)

Storm Relative Helicity (SRH) measures the potential for rotating updrafts by combining low-level wind shear with the storm motion vector.

Question 47: Sea and land breezes are primarily driven by what mechanism?

Differential heating between land and water surfaces (Correct answer)
Upper-level divergence
Coriolis force at the coast
Orographic lifting

Correct answer: Differential heating between land and water surfaces

Sea and land breezes result from differential heating — land warms faster than water during the day, creating a pressure gradient that drives onshore flow.

Question 48: The Atlantic Multidecadal Oscillation (AMO) has been linked most strongly to variations in:

Western European drought frequency and North Atlantic hurricane activity (Correct answer)
Indian Ocean dipole events
Pacific trade wind intensity and ENSO amplitude
Antarctic ice shelf calving rates

Correct answer: Western European drought frequency and North Atlantic hurricane activity

The AMO, a pattern of North Atlantic SST variability with 60–80 year cycles, is associated with shifts in Atlantic hurricane frequency, Sahel rainfall, and summer climate anomalies across Europe and North America.

Question 49: The current rise in global mean sea level is primarily attributed to:

Increased river runoff from heavier precipitation
Redistribution of ocean water by changing circulation patterns
Thermal expansion of seawater and mass loss from glaciers and ice sheets (Correct answer)
Tectonic subsidence of ocean floors

Correct answer: Thermal expansion of seawater and mass loss from glaciers and ice sheets

Current sea level rise is driven roughly equally by thermal expansion of warming ocean water and by mass contributions from melting mountain glaciers and the Greenland and Antarctic ice sheets.

Question 50: What type of mesoscale convective system organizes into a line of thunderstorms?

Air mass thunderstorm
Mesoscale convective complex (MCC)
Supercell
Squall line (Correct answer)

Correct answer: Squall line

A squall line is a linear band of convective storms organized by wind shear, often producing widespread damaging winds.

Question 51: What does divergence in the upper atmosphere typically indicate at the surface?

Stable air mass
Surface high pressure
No surface weather
Surface low pressure and rising motion (Correct answer)

Correct answer: Surface low pressure and rising motion

Upper-level divergence removes mass from a column, lowering surface pressure and promoting rising motion.

Question 52: Infrared (IR) satellite imagery detects what property to infer cloud heights?

Cloud top temperature (colder = higher) (Correct answer)
Cloud thickness
Cloud water content
Cloud albedo (reflectivity)

Correct answer: Cloud top temperature (colder = higher)

IR satellite detects emitted thermal radiation; since temperature decreases with altitude, colder cloud tops appear brighter and indicate higher clouds.

Question 53: What is a Mesoscale Convective Complex (MCC)?

A single large supercell thunderstorm
A large, long-lived organized convective system with a circular cold cloud shield (Correct answer)
A winter storm with embedded convection
A cluster of sea breeze cells

Correct answer: A large, long-lived organized convective system with a circular cold cloud shield

An MCC is a large, nearly circular mesoscale convective system defined by specific cloud shield area and duration criteria in IR satellite imagery.

Question 54: What is the thermal wind relationship?

Wind direction rotates clockwise with height in all situations
Wind speed at the surface equals wind speed aloft
Vertical wind shear is related to horizontal temperature gradients (Correct answer)
Temperature increases with height in the stratosphere

Correct answer: Vertical wind shear is related to horizontal temperature gradients

The thermal wind relationship states that vertical wind shear in geostrophic flow is proportional to horizontal temperature gradients.

Question 55: What is the f-plane approximation in dynamic meteorology?

Treating the Coriolis parameter as constant with latitude (Correct answer)
Ignoring vertical motion entirely
Treating Earth as flat with constant gravity
Assuming frictionless flow near the surface

Correct answer: Treating the Coriolis parameter as constant with latitude

The f-plane approximation holds the Coriolis parameter constant at its local value, simplifying equations for small-scale analysis.

Question 56: What is the Bright Band in radar meteorology?

High reflectivity return from the jet stream
A horizontal beam blockage artifact
Enhanced returns from urban areas
An enhanced reflectivity layer near the melting level where snowflakes partially melt (Correct answer)

Correct answer: An enhanced reflectivity layer near the melting level where snowflakes partially melt

The bright band is an elevated layer of high radar reflectivity caused by partially melted snowflakes presenting a larger effective radar cross-section.

Question 57: What is the Bergen School cyclone model?

A forecasting algorithm for winter storms
A tropical cyclone intensification theory
A mesoscale convective system model
The Norwegian model describing extratropical cyclone life cycle (Correct answer)

Correct answer: The Norwegian model describing extratropical cyclone life cycle

The Norwegian (Bergen School) cyclone model describes how extratropical cyclones develop, mature, and occlude.

Question 58: What does the CIN (Convective Inhibition) represent on a sounding?

Maximum updraft speed
Boundary layer moisture content
Energy that must be overcome by lifting to reach the LFC (Correct answer)
Energy available for downdrafts

Correct answer: Energy that must be overcome by lifting to reach the LFC

CIN represents the negative buoyancy energy that must be overcome before a parcel can reach the LFC and convect freely.

Question 59: What meteorological tool provides vertical profiles of temperature, humidity, and wind at a specific location?

Satellite IR imagery
Radiosonde sounding (Correct answer)
Surface ASOS station
Radar reflectivity

Correct answer: Radiosonde sounding

Radiosondes are balloon-borne instruments that measure atmospheric temperature, humidity, pressure, and wind through the troposphere.

Question 60: What does the K-Index measure in severe weather forecasting?

Hail size potential
Tornado probability
Upper-level divergence
Thunderstorm potential based on temperature, dew point, and lapse rate (Correct answer)

Correct answer: Thunderstorm potential based on temperature, dew point, and lapse rate

The K-Index combines low-level moisture, temperature lapse rate, and mid-level moisture saturation to estimate thunderstorm potential.

Question 61: The 'hockey stick' reconstruction of Northern Hemisphere temperatures, first published by Mann et al. (1999), is significant because it illustrates:

A sudden collapse of temperatures at the start of the industrial revolution
An abrupt cooling event linked to the Little Ice Age that ended in the 13th century
Relatively stable medieval temperatures followed by rapid warming in the 20th century unlike anything in the past millennium (Correct answer)
Cyclical warm and cold periods of equal magnitude throughout the past 2,000 years

Correct answer: Relatively stable medieval temperatures followed by rapid warming in the 20th century unlike anything in the past millennium

The reconstruction showed a relatively flat shaft of roughly stable temperatures over the past ~900 years followed by a sharp 20th-century upturn (the blade), demonstrating that recent warming is unprecedented in at least 1,000 years.

Question 62: On a surface weather map, isobars that are closely spaced indicate what?

Weak pressure gradient and calm winds
Stable air
Strong pressure gradient and strong winds (Correct answer)
High humidity

Correct answer: Strong pressure gradient and strong winds

Closely spaced isobars indicate a steep pressure gradient, which drives stronger winds.

Question 63: In hydrological forecasting, what is the Flash Flood Guidance (FFG) product?

A forecast of river stage at gauging stations
A satellite product showing flood inundation
A warning issued when flood waters rise above flood stage
The amount of rainfall needed over a specific duration to initiate flash flooding in a given area (Correct answer)

Correct answer: The amount of rainfall needed over a specific duration to initiate flash flooding in a given area

FFG represents the rainfall amount required over a specified duration (1, 3, 6 hours) to cause small stream flooding in a given hydrologic area.

Question 64: What is the purpose of ASOS (Automated Surface Observing System) stations in the US?

Wind profiling
Upper-air radiosonde launches
Lightning mapping
Automated surface weather observations for aviation and public use (Correct answer)

Correct answer: Automated surface weather observations for aviation and public use

ASOS stations provide automated, continuous surface weather observations including temperature, dew point, wind, visibility, and present weather.

Question 65: GPS radio occultation provides which type of atmospheric data?

Wind speed from Doppler shift
Temperature and humidity profiles from GPS signal refraction (Correct answer)
Surface precipitation estimates
Cloud liquid water path

Correct answer: Temperature and humidity profiles from GPS signal refraction

GPS radio occultation measures bending of GPS signals through the atmosphere to retrieve temperature, humidity, and pressure profiles globally.

Question 66: Which surface feature is commonly found along the boundary between dry continental and moist Gulf of Mexico air in the US?

Cold front
Dryline (Correct answer)
Occluded front
Warm front

Correct answer: Dryline

The dryline is a moisture boundary common over the US Great Plains, separating moist Gulf air from dry continental air.

Question 67: Lightning detection networks like the US NLDN measure what properties of lightning strokes?

Cloud charge distribution only
Thunder duration
Location, time, polarity, and peak current of lightning strikes (Correct answer)
Flash optical intensity

Correct answer: Location, time, polarity, and peak current of lightning strikes

The National Lightning Detection Network (NLDN) uses time-of-arrival techniques to detect and locate cloud-to-ground lightning, measuring peak current, polarity, and time.

Question 68: What is the MSLP (Mean Sea Level Pressure) standard value for a typical atmospheric surface?

950 hPa
1050 hPa
1000 hPa
1013.25 hPa (Correct answer)

Correct answer: 1013.25 hPa

The standard mean sea level pressure is 1013.25 hPa (or approximately 29.92 inches of mercury).

Question 69: What is Rapid Intensification (RI) of a tropical cyclone defined as?

Doubling of storm size in 24 hours
An increase of at least 35 mph in maximum sustained winds within 24 hours (Correct answer)
Any increase in wind speed over 48 hours
A 10 hPa central pressure drop in 12 hours

Correct answer: An increase of at least 35 mph in maximum sustained winds within 24 hours

The NHC defines Rapid Intensification as an increase of at least 35 knots (~40 mph) in maximum sustained winds within 24 hours.

Question 70: What is the Fujita Scale (F-scale) or Enhanced Fujita Scale (EF-scale) used to measure?

Tornado path length
Tornado intensity based on wind damage indicators (Correct answer)
Hail size distribution
Rotation velocity in mesocyclones

Correct answer: Tornado intensity based on wind damage indicators

The Enhanced Fujita Scale rates tornado intensity from EF0 to EF5 based on observed damage to structures and vegetation.

Question 71: What does the Velocity Azimuth Display (VAD) technique provide from Doppler radar data?

Hail size estimates
Precipitation rate estimates
Vertical wind profiles at the radar site (Correct answer)
Storm motion vectors

Correct answer: Vertical wind profiles at the radar site

The VAD technique uses a full 360° radar scan at constant elevation to derive mean wind speed and direction as a function of altitude.

Question 72: Which surface type has the highest typical albedo?

Desert sand
Fresh dry snow (Correct answer)
Dense tropical rainforest
Open ocean under clear skies

Correct answer: Fresh dry snow

Fresh dry snow has an albedo of 0.80–0.90, reflecting most incoming solar radiation, which is why snow-covered regions remain cold and why ice-albedo feedback amplifies climate change.

Question 73: An outflow boundary is a mesoscale boundary created by what?

The spreading cool downdraft air from convective storms (Correct answer)
A cold front reaching the surface
Orographic flow splitting around mountains
A sea breeze penetrating inland

Correct answer: The spreading cool downdraft air from convective storms

Outflow boundaries form at the leading edge of cold pool air from thunderstorm downdrafts and can trigger new convection.

Question 74: What is a cold pool in convective meteorology?

The region of cold air above a thunderstorm anvil
A cold air mass over the Arctic
A cold front boundary
A pool of cold, dense air at the surface formed by evaporative cooling from precipitation (Correct answer)

Correct answer: A pool of cold, dense air at the surface formed by evaporative cooling from precipitation

A cold pool is a dense, cool air mass at the surface created by evaporation of precipitation and downdraft air spreading from thunderstorms.

Question 75: Water vapor satellite imagery detects radiation in what spectral band?

Visible light (~0.5 μm)
Near-infrared (~1.6 μm)
Water vapor absorption band (~6.2–7.3 μm) (Correct answer)
Thermal window (~10.7 μm)

Correct answer: Water vapor absorption band (~6.2–7.3 μm)

Water vapor imagery uses the 6.2–7.3 μm absorption band where water vapor absorbs and re-emits radiation, revealing moisture in the mid-to-upper troposphere.

Question 76: What does Doppler radar velocity data measure that standard reflectivity cannot?

Precipitation type
Radial wind velocity (toward or away from the radar) (Correct answer)
Lightning frequency
Cloud thickness

Correct answer: Radial wind velocity (toward or away from the radar)

Doppler radar measures the phase shift of returned radar pulses to determine the radial velocity of precipitation moving toward or away from the radar.

Question 77: What is the primary balance in the tropics that replaces geostrophic balance?

Gradient wind balance
Cyclostrophic balance (Correct answer)
Hydrostatic balance
Anelastic balance

Correct answer: Cyclostrophic balance

In strong tropical vortices where Coriolis force is negligible, cyclostrophic balance between the centrifugal and pressure gradient forces dominates.

Question 78: Virtual temperature is used in atmospheric thermodynamics to account for what effect?

Diurnal temperature variation
Urban heat island effects
Radiative cooling at night
The effect of water vapor on air buoyancy and density (Correct answer)

Correct answer: The effect of water vapor on air buoyancy and density

Virtual temperature treats moist air as equivalent dry air, accounting for the lower density of water vapor relative to dry air.

Question 79: The WSR-88D radar network in the United States is also known by what acronym?

GOES
AWIPS
NEXRAD (Correct answer)
ASOS

Correct answer: NEXRAD

The WSR-88D network is known as NEXRAD (Next Generation Weather Radar), the backbone of operational weather surveillance in the US.

Question 80: In synoptic analysis, what does 'vorticity advection' describe?

Surface pressure tendency
Horizontal transport of spin by the wind (Correct answer)
Vertical transport of heat
Moisture flux convergence

Correct answer: Horizontal transport of spin by the wind

Vorticity advection refers to the horizontal transport of vorticity by the wind field, which drives vertical motion.

Question 81: Which greenhouse gas has the highest global warming potential (GWP) per molecule over a 100-year time horizon?

Methane (CH4)
Nitrous oxide (N2O)
Carbon dioxide (CO2)
Sulfur hexafluoride (SF6) (Correct answer)

Correct answer: Sulfur hexafluoride (SF6)

SF6 has a GWP of approximately 23,500 over 100 years, far exceeding CO2, CH4, and N2O on a per-molecule basis.

Question 82: What does potential vorticity conservation imply for a column of air that stretches vertically?

Its relative vorticity increases (Correct answer)
Its absolute vorticity decreases
Its pressure increases
It warms adiabatically

Correct answer: Its relative vorticity increases

When an air column stretches, relative vorticity must increase to conserve potential vorticity.

Question 83: The Quasi-Biennial Oscillation (QBO) refers to:

A two-year variation in global mean surface temperature
A biennial oscillation in Arctic sea ice extent
A roughly 2-year alternating pattern of easterly and westerly winds in the tropical stratosphere (Correct answer)
A 2-year cycle of precipitation in the tropical troposphere

Correct answer: A roughly 2-year alternating pattern of easterly and westerly winds in the tropical stratosphere

The QBO is a downward-propagating pattern of alternating equatorial stratospheric zonal winds at about 10–50 hPa, with a mean period of approximately 28 months, influencing storm tracks and tropospheric weather.

Question 84: What is the role of the low-level jet (LLJ) in Great Plains severe weather?

It suppresses convection through warm advection
It creates cold air pooling in valleys
It drives upper-level divergence directly
It transports moisture northward and enhances wind shear for severe thunderstorms (Correct answer)

Correct answer: It transports moisture northward and enhances wind shear for severe thunderstorms

The nocturnal LLJ over the Great Plains advects Gulf moisture northward and creates significant low-level wind shear, supporting nocturnal convection.

Question 85: What is the El Niño-Southern Oscillation (ENSO) and how does it affect US winter weather?

A short-term weather pattern affecting only the Pacific Ocean
A coupled ocean-atmosphere oscillation that modulates global climate; El Niño typically brings wetter conditions to southern US and drier/warmer to the north (Correct answer)
A stratospheric oscillation affecting polar vortex strength
A seasonal shift that only impacts tropical regions

Correct answer: A coupled ocean-atmosphere oscillation that modulates global climate; El Niño typically brings wetter conditions to southern US and drier/warmer to the north

ENSO alternates between El Niño (warm Pacific SSTs) and La Niña (cool SSTs), creating significant teleconnections that shift storm tracks and temperature patterns across the US.

Question 86: What is the purpose of dual-polarization radar technology?

Increase radar range
Reduce ground clutter
Distinguish precipitation types (rain, snow, hail, graupel) and improve QPE (Correct answer)
Measure upper-level winds

Correct answer: Distinguish precipitation types (rain, snow, hail, graupel) and improve QPE

Dual-polarization radar transmits both horizontal and vertical pulses, allowing discrimination of hydrometeor types and improving quantitative precipitation estimates.

Question 87: What is a Mesoscale Convective System (MCS)?

A complex of thunderstorms organized on the mesoscale with a contiguous precipitation area (Correct answer)
A tropical wave system
A synoptic-scale trough system
Any single severe thunderstorm

Correct answer: A complex of thunderstorms organized on the mesoscale with a contiguous precipitation area

An MCS is a complex of convective storms that forms a large, contiguous precipitation area organized on the mesoscale (100–2000 km).

Question 88: Tornadogenesis in supercells is most commonly associated with what process?

Downward transport of mesocyclone vorticity to the surface (Correct answer)
Cold front passage only
High CAPE with no wind shear
Upper-level jet streak left exit region

Correct answer: Downward transport of mesocyclone vorticity to the surface

Tornadogenesis involves stretching and tilting of near-surface horizontal vorticity into the vertical, amplified by the supercell's rotating updraft.

Question 89: A supercell thunderstorm is distinguished by what primary feature?

Multicell cluster organization
Very slow movement
A persistent, deep rotating updraft (mesocyclone) (Correct answer)
Weak rotation and shallow depth

Correct answer: A persistent, deep rotating updraft (mesocyclone)

Supercells are defined by a deep, persistent rotating updraft called a mesocyclone, which enables long-lived, organized severe convection.

Question 90: What is a Weather Watch vs. Warning distinction in NWS severe weather products?

A Watch means severe weather is occurring; a Warning is the forecast outlook
They are interchangeable terms
A Watch means conditions are favorable for severe weather; a Warning means severe weather is occurring or imminent (Correct answer)
Watches are county-based; warnings are state-based

Correct answer: A Watch means conditions are favorable for severe weather; a Warning means severe weather is occurring or imminent

NWS Watches indicate conditions are favorable for severe weather development, while Warnings indicate severe weather is imminent or occurring.

Question 91: What is the primary external driver of Earth's climate system?

Ocean thermohaline circulation
Tidal forces from the Moon
Geothermal heat from Earth's interior
Solar radiation (Correct answer)

Correct answer: Solar radiation

Solar radiation is the dominant energy input that drives atmospheric circulation, ocean currents, and the global climate system.

Question 92: What does radar reflectivity (dBZ) measure in meteorological applications?

Cloud top temperature
Wind speed and direction
Intensity of precipitation by measuring returned energy from hydrometeors (Correct answer)
Atmospheric pressure

Correct answer: Intensity of precipitation by measuring returned energy from hydrometeors

Radar reflectivity (dBZ) measures the intensity of returned microwave energy from precipitation particles, indicating rainfall or snowfall rates.

Question 93: El Niño conditions in the tropical Pacific are characterized by:

Warmer-than-normal SSTs in the central and eastern tropical Pacific (Correct answer)
Higher-than-normal sea level pressure in the central Pacific
Stronger-than-normal Walker circulation and trade winds
Cooler-than-normal SSTs across the entire tropical Pacific

Correct answer: Warmer-than-normal SSTs in the central and eastern tropical Pacific

El Niño is defined by anomalously warm sea surface temperatures in the central and eastern equatorial Pacific, which weaken the Walker circulation and alter global weather patterns.

Question 94: The Köppen climate classification system primarily categorizes climates based on:

Atmospheric pressure and prevailing wind direction
Temperature and precipitation patterns (Correct answer)
Solar radiation and surface albedo
Relative humidity and cloud cover frequency

Correct answer: Temperature and precipitation patterns

Köppen's system uses monthly and annual temperature and precipitation thresholds, along with seasonal patterns, to define five major climate zones and their subtypes.

Question 95: The moist adiabatic lapse rate (MALR) is approximately what value near the surface?

9.8°C/km
1°C/km
12°C/km
4–7°C/km (Correct answer)

Correct answer: 4–7°C/km

The MALR varies from about 4°C/km in warm moist air to 7°C/km in cooler air, less than the DALR due to latent heat release.

Question 96: What type of lapse rate produces absolutely unstable conditions?

Isothermal layer
Lapse rate equal to the MALR
Lapse rate greater than the DALR (Correct answer)
Lapse rate less than the MALR

Correct answer: Lapse rate greater than the DALR

Absolute instability occurs when the environmental lapse rate exceeds the dry adiabatic lapse rate (~9.8°C/km), causing any parcel to accelerate upward.

Question 97: The globally averaged mean surface temperature of Earth is approximately:

25°C (77°F)
0°C (32°F)
10°C (50°F)
15°C (59°F) (Correct answer)

Correct answer: 15°C (59°F)

Earth's global mean surface temperature is approximately 15°C (288 K), which is about 33°C warmer than it would be without the natural greenhouse effect.

Question 98: What is a cutoff low?

A shallow low formed by surface heating
An upper-level low that has separated from the main westerly flow (Correct answer)
A low-pressure system over the ocean only
A surface low with no associated precipitation

Correct answer: An upper-level low that has separated from the main westerly flow

A cutoff low is an isolated upper-level low pressure center that has detached from the main jet stream flow.

Question 99: On a Skew-T log-P diagram, the dew point profile indicates what?

Cloud top height
Temperature inversions only
Wind speed at each level
Moisture content as a function of pressure (Correct answer)

Correct answer: Moisture content as a function of pressure

The dew point profile on a Skew-T shows the moisture content of the atmosphere as a function of pressure level.

Question 100: What is the primary purpose of data assimilation in NWP?

Downscaling global models to regional scales
Creating climate model scenarios
Generating ensemble members
Optimally combining model background fields with new observations to create the best initial state for forecasts (Correct answer)

Correct answer: Optimally combining model background fields with new observations to create the best initial state for forecasts

Data assimilation merges model background states with observations using statistical methods to produce the optimal analysis for initializing NWP forecasts.

AMS Certified Broadcast Meteorologist (CBM)

The AMS Certified Broadcast Meteorologist (CBM) certification validates professional-level knowledge of atmospheric science and meteorology required for effective broadcast meteorology, including synoptic analysis, mesoscale dynamics, remote sensing, and numerical weather prediction.

100

Questions

120 min

Time Limit

75%

To Pass

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