Firefighter 1C Wildland Practice Exam

What happens to the relative humidity as the temperature warms up during the day?

1. It goes up

2. It goes down until it reaches optimum, then it goes up

3. Nothing; it is not affected by temperature change

4. It goes down

The correct answer is: It goes down

As the temperature warms up during the day, relative humidity decreases. This relationship exists because relative humidity is a measure of how much moisture is in the air compared to the maximum amount of moisture that air can hold at a given temperature. Warmer air has the capacity to hold more water vapor than cooler air. As the temperature rises, while the total amount of moisture in the air may remain constant, the increased capacity of the air to hold water means that the relative humidity will drop. This is particularly important for firefighters and those working in wildland areas to understand, as lower humidity levels can lead to drier conditions, influencing fire behavior and spread.