Fire Weather Wildland Firefighting Exam With Complete
Solutions 100% Correct
Weather factors that influence the ignition and spread of wildland fires include: (4) -
ANSWER 1) Wind
2) Relative humidity
3) Temperature
4) Precipitation
Warm air can hold more moisture. So as the air temperature rises during the day the
relative humidity will decrease and affect fire behavior whereas as the temperature
cools in the evening and night the relative humidity will _______ - ANSWER increase
Aspect and elevation affect both temperature and relative humidity. Studies indicate
that southern aspects are generally ____ degrees warmer than northern aspects,
primarily due to more direct solar radiation. - ANSWER five
The highest daytime temperature and lower relative humidities are found near the
______ of the trees. - ANSWER crowns
Lapse Rates
Lapse rate is defined as the change in temperature caused by a change in ________.
However, lapse rate is affected both by elevation and the moisture in the air.
Temperature decreases as elevation increases. - ANSWER altitude
The average Lapse rate is about ±_____ per 1,000 feet of elevation change - ANSWER
3.5°
Unstable air can intensify fire behavior by increasing:
, ■ The chance of dust devils and firewhirls.
■ The possibility of gusty surface winds. Strong winds aloft can be brought down
toward the surface
■ The height and strength of convection columns. When the atmosphere is unstable,
convection columns will rise to greater heights and with greater speed. This causes
stronger inward drafts (winds).
■ The possibility of spot fires. Tall, well-developed convection columns lift more
firebrands - ANSWER
Visible signs of stable air
■ Clouds in layers, no vertical motion; stratus type clouds
■ Smoke column drifts apart after limited rise
■ Poor visibility in lower levels due to accumulation of haze and smoke
■ _______ winds
■ Cooler at lower elevations; fog layers - ANSWER Steady
Visible indications of unstable air
■ Clouds grow vertically; cumulus type clouds
■ Upward and downward currents; smoke rises to great heights; gusty winds
■ Good visibility
■ Dust devils and/or firewhirls
■ _______ at lower elevations - ANSWER Warmer
___________ is a layer very stable air where, contrary to normal behavior, the
temperature rises as the altitude increases. - ANSWER inversion layer
An inversion layer acts as a lid or blanket over cooler air. Air rises when warm air is
surrounded by cooler air. Cool air will not rise through the warm air. Because of this,
inversion layers severely limit vertical motion in the atmosphere. Smoke generated by a
Solutions 100% Correct
Weather factors that influence the ignition and spread of wildland fires include: (4) -
ANSWER 1) Wind
2) Relative humidity
3) Temperature
4) Precipitation
Warm air can hold more moisture. So as the air temperature rises during the day the
relative humidity will decrease and affect fire behavior whereas as the temperature
cools in the evening and night the relative humidity will _______ - ANSWER increase
Aspect and elevation affect both temperature and relative humidity. Studies indicate
that southern aspects are generally ____ degrees warmer than northern aspects,
primarily due to more direct solar radiation. - ANSWER five
The highest daytime temperature and lower relative humidities are found near the
______ of the trees. - ANSWER crowns
Lapse Rates
Lapse rate is defined as the change in temperature caused by a change in ________.
However, lapse rate is affected both by elevation and the moisture in the air.
Temperature decreases as elevation increases. - ANSWER altitude
The average Lapse rate is about ±_____ per 1,000 feet of elevation change - ANSWER
3.5°
Unstable air can intensify fire behavior by increasing:
, ■ The chance of dust devils and firewhirls.
■ The possibility of gusty surface winds. Strong winds aloft can be brought down
toward the surface
■ The height and strength of convection columns. When the atmosphere is unstable,
convection columns will rise to greater heights and with greater speed. This causes
stronger inward drafts (winds).
■ The possibility of spot fires. Tall, well-developed convection columns lift more
firebrands - ANSWER
Visible signs of stable air
■ Clouds in layers, no vertical motion; stratus type clouds
■ Smoke column drifts apart after limited rise
■ Poor visibility in lower levels due to accumulation of haze and smoke
■ _______ winds
■ Cooler at lower elevations; fog layers - ANSWER Steady
Visible indications of unstable air
■ Clouds grow vertically; cumulus type clouds
■ Upward and downward currents; smoke rises to great heights; gusty winds
■ Good visibility
■ Dust devils and/or firewhirls
■ _______ at lower elevations - ANSWER Warmer
___________ is a layer very stable air where, contrary to normal behavior, the
temperature rises as the altitude increases. - ANSWER inversion layer
An inversion layer acts as a lid or blanket over cooler air. Air rises when warm air is
surrounded by cooler air. Cool air will not rise through the warm air. Because of this,
inversion layers severely limit vertical motion in the atmosphere. Smoke generated by a
