Book 7, Question 18
Why Do Some Days Feel Sticky Before It Rains?
Before many storms, the air is full of water vapor, so the humidity is high. When the air is that damp, your sweat has a hard time drying off. That leftover moisture on your skin is why the day feels sticky.
From the book
Page from A Million Whys Book 7
More fun facts
- There is an old saying: it's not the heat, it's the humidity. Scientists say it's really both.
- Your body cools off by sending more blood near the skin and by sweating.
- Sweat cools you when your body heat turns it into water vapor, which carries heat away.
- Once the air reaches about 95 degrees Fahrenheit, close to body temperature, your body can't lose much heat to the air, so sweating becomes the main way to cool off.
- The heat index, or feels-like temperature, combines air temperature and humidity.
- In Dhahran, Saudi Arabia, in 2003, the air was 108 degrees Fahrenheit, but with the humidity the heat index was 178 degrees.
Questions kids ask
What is the heat index?
A feels-like temperature that combines air temperature and humidity.
How does sweat cool you down?
Body heat turns sweat into water vapor, and the vapor carries heat away.