S-130 Weather Observation 2 — Questions and Answers
Question 1: What is the term for the layer of air closest to the earth's surface where most weather occurs?
- Stratosphere
- Troposphere (Correct answer)
- Mesosphere
- Thermosphere
Correct answer: Troposphere
The troposphere is the lowest atmospheric layer and the zone where virtually all weather phenomena, including fire weather, occur.
Question 2: Which instrument measures atmospheric pressure and is used to help forecast approaching weather systems?
- Hygrometer
- Anemometer
- Barometer (Correct answer)
- Psychrometer
Correct answer: Barometer
A barometer measures atmospheric pressure; falling pressure often indicates an approaching storm or weather change relevant to fire behavior.
Question 3: A firefighter observes cumulus clouds building rapidly into towering cumulonimbus clouds overhead. This indicates:
- Stable air and steady winds
- Possible thunderstorm activity and erratic winds (Correct answer)
- Decreasing relative humidity only
- A cold front has already passed
Correct answer: Possible thunderstorm activity and erratic winds
Rapid vertical development into cumulonimbus signals convective instability and potential for thunderstorm-generated erratic outflow winds and dry lightning.
Question 4: What does a lapse rate describe in fire weather meteorology?
- The decrease in wind speed with altitude
- The rate at which temperature decreases with increasing altitude (Correct answer)
- The increase in relative humidity at night
- The rate of fuel moisture loss over time
Correct answer: The rate at which temperature decreases with increasing altitude
Lapse rate is the rate of temperature decrease with altitude; a steep lapse rate indicates atmospheric instability that promotes fire development.
Question 5: Which type of wind is caused by the local heating of slopes during the day, causing air to flow uphill?
- Katabatic wind
- Anabatic wind (Correct answer)
- Foehn wind
- Diurnal drainage wind
Correct answer: Anabatic wind
Anabatic winds are upslope winds driven by daytime solar heating of mountain slopes, which can carry fire uphill rapidly.
Question 6: During a spot weather forecast request, which information about your fire location is MOST critical to provide to the meteorologist?
- The number of firefighters on scene
- Elevation, aspect, and slope steepness (Correct answer)
- The type of suppression equipment being used
- The size of the fire in acres
Correct answer: Elevation, aspect, and slope steepness
Elevation, aspect, and slope steepness determine local wind patterns, temperature, and humidity, allowing meteorologists to tailor the forecast accurately.
Question 7: What is the primary danger posed by a temperature inversion in relation to wildland fire?
- It cures fuels faster making them more flammable
- It traps smoke near the ground reducing visibility and may suddenly break releasing unstable air (Correct answer)
- It prevents fire from spreading upslope
- It always increases relative humidity above fire danger thresholds
Correct answer: It traps smoke near the ground reducing visibility and may suddenly break releasing unstable air
A temperature inversion can trap smoke and suppress fire activity temporarily, but when it breaks it releases unstable air that can cause rapid fire acceleration.
S-130 Weather Observation 2
What is the term for the layer of air closest to the earth's surface where most weather occurs?