S-130 Weather Observation 3

Question 1

What is the relative humidity level generally considered critically low, significantly increasing fire danger in wildland firefighting?

Accepted Answer

Below 25%

Answer

Relative humidity below 25% is typically considered critically low, causing rapid drying of fine fuels and sharply increasing fire danger and spread rates.

Question 2

A firefighter notes the wind direction has shifted 180 degrees and speed has increased. This is MOST likely associated with:

Accepted Answer

Passage of a frontal system

Answer

A sudden 180-degree wind shift combined with increasing speed is a classic indicator of frontal passage, which can cause extreme fire behavior.

Question 3

What does the term 'fine fuel moisture content' refer to in fire weather observation?

Accepted Answer

The moisture percentage in 1-hour timelag fuels like grass and dead needles

Answer

Fine fuel moisture refers to the moisture content of small-diameter, fast-drying fuels such as grasses and dead needles that respond quickly to atmospheric changes.

Question 4

Which cloud type is most associated with stable atmospheric conditions and generally lower fire danger from wind?

Accepted Answer

Stratus

Answer

Stratus clouds form in stable, layered air with little vertical mixing, indicating calm conditions less likely to produce erratic fire-driving winds.

Question 5

How does increasing elevation generally affect temperature and relative humidity in mountainous fire environments?

Accepted Answer

Temperature decreases and humidity generally increases

Answer

As elevation increases, air temperature typically decreases at the environmental lapse rate while relative humidity tends to increase, affecting fuel drying rates.

(S-130) Wildland Firefighting Training Certification Practice Test

(S-130) Wildland Firefighting Training Certification Practice Test

S-130 Weather Observation 3