Wildland Firefighting Practice Exam

How much is the humidity reduced for every 20 degrees in temperature?

1. One quarter

2. One third

3. One half

4. One whole

The correct answer is: One half

The relationship between temperature and relative humidity is significant in understanding weather and fire behavior. Specifically, as the temperature increases, the air's capacity to hold moisture also increases, leading to a decrease in relative humidity. A common rule of thumb in meteorology states that relative humidity decreases by about 50 percent for every increase of 20 degrees Fahrenheit in temperature. This decrease in humidity is crucial for wildland firefighting, as lower humidity levels can correspond to higher fire danger. When temperatures rise, the dry air can exacerbate fire behavior, allowing flames to spread more rapidly and making control efforts more challenging. Consequently, recognizing the impact of temperature on humidity helps firefighters assess the potential for fire spread and take appropriate precautions, emphasizing the importance of monitoring weather conditions in wildfire management.