Boiling and Evaporation

Both boiling and evaporation turn liquid water into water vapor, a gas. But they work differently. Boiling happens when water is heated to a high temperature and bubbles form throughout the liquid. Evaporation happens slowly at the surface of a liquid, even at lower temperatures.

Boiling

When water is heated to 212 degrees Fahrenheit at sea level, it boils. Bubbles of water vapor form throughout the liquid and rise to the surface. The water changes from liquid to gas very quickly. The temperature of boiling water stays the same until all the water has turned to steam.

Evaporation

Evaporation happens at any temperature, not just at the boiling point. Particles at the surface of a liquid sometimes have enough energy to escape into the air. This is why a puddle dries up on a warm day even though the water never boils. Wind and warmth speed up evaporation.

Fun Facts

• At the top of Mount Everest, water boils at about 160 degrees Fahrenheit because of lower air pressure.
• Evaporation makes you feel cool when you step out of a swimming pool because it pulls heat from your skin.
• The Dead Sea loses about a billion gallons of water per year to evaporation.

Did You Know?

If you could watch water molecules up close, you would see them bouncing around. Some molecules at the surface bounce hard enough to fly right off the liquid and into the air. That is evaporation in action!