AMS Certified Broadcast Meteorologist (CBM) — Questions and Answers

Question 1: Equivalent potential temperature (theta-e) is conserved in which atmospheric process?

Radiative cooling
Both dry and moist (saturated) adiabatic processes (Correct answer)
Dry adiabatic ascent only
Diabatic heating

Correct answer: Both dry and moist (saturated) adiabatic processes

Theta-e is conserved during both dry and moist adiabatic processes, making it useful for tracing air masses through phase changes.

Question 2: What is the purpose of dual-polarization radar technology?

Distinguish precipitation types (rain, snow, hail, graupel) and improve QPE (Correct answer)
Reduce ground clutter
Increase radar range
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 3: A supercell thunderstorm is distinguished by what primary feature?

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

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 4: GPS radio occultation provides which type of atmospheric data?

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

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 5: The Model Output Statistics (MOS) technique improves NWP forecasts by doing what?

Using only the most recent model run
Running the model at higher resolution
Combining multiple models equally
Applying statistical relationships between model output and observed weather to reduce systematic errors (Correct answer)

Correct answer: Applying statistical relationships between model output and observed weather to reduce systematic errors

MOS uses regression relationships derived from historical model errors and observations to generate bias-corrected, site-specific forecast guidance.

Question 6: What is the purpose of ASOS (Automated Surface Observing System) stations in the US?

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

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

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

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 8: What is a Mesoscale Convective System (MCS)?

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

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

9.8°C/km
12°C/km
1°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 10: A zonal flow pattern in the mid-latitudes is characterized by what?

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

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

Projections of sea level rise under different ocean warming scenarios
Varied assumptions about aerosol concentrations in future climate models
Different assumptions about future greenhouse gas emissions and societal development trajectories (Correct answer)
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 12: During rapid cyclogenesis (bombogenesis), how much must surface pressure drop in 24 hours?

At least 36 hPa in 48 hours
At least 12 hPa in 24 hours
At least 24 hPa in 24 hours (latitude-corrected) (Correct answer)
At least 6 hPa in 12 hours

Correct answer: At least 24 hPa in 24 hours (latitude-corrected)

Bombogenesis is defined as a surface low deepening by at least 1 Bergeron (24 hPa/24 hrs adjusted to 60°N) in 24 hours.

Question 13: The globally averaged mean surface temperature of Earth is approximately:

0°C (32°F)
25°C (77°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 14: Which layer in the atmosphere separates the troposphere from the stratosphere?

Stratopause
Thermopause
Tropopause (Correct answer)
Mesopause

Correct answer: Tropopause

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

Question 15: 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 16: What does PVU (potential vorticity unit) measure?

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

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 17: What force causes wind to deflect to the right in the Northern Hemisphere?

Centrifugal force
Gravity
Coriolis force (Correct answer)
Pressure gradient force

Correct answer: Coriolis force

The Coriolis force, caused by Earth's rotation, deflects moving air to the right in the Northern Hemisphere.

Question 18: What is potential temperature (theta) and why is it useful?

Temperature a parcel would have if brought adiabatically to 1000 hPa; conserved in dry adiabatic motion (Correct answer)
Temperature at a fixed altitude; useful for comparing elevations
Temperature corrected for moisture; used in tropical analysis
Effective temperature felt by observers at the surface

Correct answer: Temperature a parcel would have if brought adiabatically to 1000 hPa; conserved in dry adiabatic motion

Potential temperature is conserved during dry adiabatic processes, making it ideal for identifying airmass properties and stability.

Question 19: The Brunt-Väisälä frequency measures what atmospheric property?

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

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

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

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 21: The Köppen climate classification system primarily categorizes climates based on:

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

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

Visible light (~0.5 μm)
Water vapor absorption band (~6.2–7.3 μm) (Correct answer)
Near-infrared (~1.6 μm)
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 23: Which parameter best describes the potential for long-track tornadoes in supercells?

CAPE alone
Significant Tornado Parameter (STP) (Correct answer)
K-Index
Total Totals 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 24: Mountain waves and associated turbulence are detected most effectively with which tool?

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

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

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

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

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

Correct answer: Squall line

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

Question 27: What is the Madden-Julian Oscillation (MJO) and how does it affect US weather?

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

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 28: Which surface type has the highest typical albedo?

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

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 29: What is a heat burst in mesoscale meteorology?

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

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 30: Aviation weather forecasts use which product to describe expected conditions at an airport over 24–30 hours?

TAF (Terminal Aerodrome Forecast) (Correct answer)
PIREP
SIGMET
METAR

Correct answer: TAF (Terminal Aerodrome Forecast)

A TAF is a standardized aviation forecast for conditions within 5 statute miles of an airport, valid for 24–30 hours.

Question 31: What is the Bergen School cyclone model?

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

Correct answer: The Norwegian model describing extratropical cyclone life cycle

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

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.

Questions

35 min

Time Limit

75%

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