What Are Clouds Made Of?

Words to Know

Water vapor

Water you can't see because it's an invisible gas in the air

Water vapor rises from oceans and lakes into the sky.

Condense

When a gas turns back into liquid because it gets cold

Water vapor condenses into tiny droplets to make clouds.

Cumulus

The big puffy clouds that look like cotton balls

Cumulus clouds are the ones you see on a sunny day.

Cirrus

Thin wispy clouds high in the sky that look like hair

Cirrus clouds are made of ice crystals because it's so cold up there.

Check What You Learned

Fun Facts

• Clouds are made of tiny water droplets and/or ice crystals suspended in the atmosphere.

  Source: NOAA National Weather Service

• Clouds form when water vapor in the air cools and condenses onto tiny particles (condensation nuclei) like dust or salt.

  Source: NASA

• A typical cumulus cloud weighs approximately 500,000 kg (about 500 metric tons). This is calculated from the water density (~0.5 g/m³) and a typical cumulus volume (~1 km³).

  Source: USGS Water Science School

• Clouds float because the warm air around them is less dense and rises, keeping the water droplets suspended.

  Source: NOAA

• The three main cloud types are: cirrus (thin, wispy, high altitude), cumulus (puffy, flat-bottomed, fair weather), and stratus (flat, layered, blanket-like).

  Source: World Meteorological Organization

• Water evaporates from oceans, lakes, and rivers, rises as invisible water vapor, and condenses at higher altitudes where temperatures are lower.

  Source: NASA Earth Observatory