Why might a 70-degree cloudy day be more dangerous to an outdoor athlete than a 80-degree dry, sunny day?

• A. You won't be sweating and evaporation occurs due to higher humidity
• B. There is more wind on cloudy days
• C. The sun is stronger on cloudy days
• D. Humidity is lower on cloudy days

Answer: (A)

The main idea is how humidity affects the body's ability to cool itself. During exercise, cooling relies largely on sweat evaporating off the skin. When humidity is high, evaporation slows down, so heat isn’t lost as efficiently. Even though the air is cooler at 70 degrees, a humid, cloudy day makes it much harder for the body to shed heat, increasing the risk of heat stress. On a dry, sunny day at 80 degrees, sweat can evaporate more readily, providing more effective cooling despite the higher temperature. So the humid, cooler day can be more dangerous because impaired evaporative cooling traps heat in the body. The other factors mentioned—wind, stronger sun on cloudy days, or lower humidity—aren’t the primary driver in this scenario.