Key Idea.
Section 1
Changing State: Gas to Liquid
We know that evaporation turns liquid water into gas. But can the reverse happen? Yes. When invisible water vapor cools down, it changes back into liquid water.
This process is called condensation. During condensation, the water molecules lose heat energy. Instead of flying apart freely, they slow down and clump together to form tiny, visible droplets. This is the exact opposite of evaporation.
Section 2
Why Cooling Matters
Temperature is the "switch" that controls the state of water. Heat turns liquid into gas (vapor). Cold turns gas back into liquid.
For condensation to occur, the air containing the water vapor must become colder. When the temperature drops, the air can no longer hold the water as a gas. The molecules represent a physical change, gathering into droplets on dust particles in the air.
Section 3
Systems Interacting
Condensation is a perfect example of Earth's systems working together. The hydrosphere (the water vapor) is interacting with the atmosphere (the cooling air).
When moist air from the hydrosphere enters a cold part of the atmosphere, condensation happens. This interaction is the first step in making clouds and rain.
Expand to review the lesson summary and core properties.
Section 1
Changing State: Gas to Liquid
We know that evaporation turns liquid water into gas. But can the reverse happen? Yes. When invisible water vapor cools down, it changes back into liquid water.
This process is called condensation. During condensation, the water molecules lose heat energy. Instead of flying apart freely, they slow down and clump together to form tiny, visible droplets. This is the exact opposite of evaporation.
Section 2
Why Cooling Matters
Temperature is the "switch" that controls the state of water. Heat turns liquid into gas (vapor). Cold turns gas back into liquid.
For condensation to occur, the air containing the water vapor must become colder. When the temperature drops, the air can no longer hold the water as a gas. The molecules represent a physical change, gathering into droplets on dust particles in the air.
Section 3
Systems Interacting
Condensation is a perfect example of Earth's systems working together. The hydrosphere (the water vapor) is interacting with the atmosphere (the cooling air).
When moist air from the hydrosphere enters a cold part of the atmosphere, condensation happens. This interaction is the first step in making clouds and rain.