Changes of State of Water

Heat energy  
Measured in calories – one calorie is the heat necessary to raise the temperature of one gram of water one degree Celsius
Latent heat
Stored or hidden heat
Not derived from temperature change
Important in atmospheric processes

Three states of matter
Solid
Liquid
Gas
To change state, heat must be
Absorbed, or
Released

Processes
Evaporation
Liquid is changed to gas
600 calories per gram of water are added – called latent heat of vaporization
Condensation
Water vapor (gas) is changed to a liquid
Heat energy is released – called latent heat of condensation

Processes
Melting  
Solid is changed to a liquid
80 calories per gram of water are added – called latent heat of melting
Freezing
Liquid is changed to a solid
Heat is released – called latent heat of fusion

Sublimation
Solid is changed directly to a gas (e.g., ice cubes shrinking in a freezer)  
680 calories per gram of water are added
Deposition
Water vapor (gas) changed to a solid (e.g., frost in a freezer compartment)  
Heat is released