THE 6 CHANGES OF STATE OF WATER
THE 6 CHANGES OF STATE OF WATER
METEOROLOGIST JEFF HABY
There are 3 states of water which are liquid, solid and gas. All three states exist on earth. Water has been  called the life force. There are names for each of the phase changes of water. They are given below:
Water going from a solid to a liquid: Melting
Water going from a liquid to a gas: Evaporation
Water going from a solid to a gas: Sublimation
Water going from a liquid to a solid: Freezing
Water going from a gas to a liquid: Condensation
Water going from a gas to a solid: Deposition
In each phase change there will be either an absorption or release of latent heat. Latent heat  absorption cools the surrounding air while latent heat release warms the surrounding air. Below are  each process and whether it absorbs or releases latent heat:
Melting: absorbs latent heat
Condensation: releases latent heat
Deposition: releases latent heat
With each phase change a specific amount of latent heat is released or absorbed. Below are the  values in two different scales which are calories per gram (cal/g) and Joules per kilogram (J/kg). Releasing  latent heat is designated as a positive number and absorbing latent heat as a negative number in this  listing to make it easier to see relative direction of heat flow relative to surrounding air.
Melting: -79.7 cal/g, -330,000 J/kg
Evaporation: -597.3 cal/g, -2,500,000 J/kg
Sublimation: -677.0 cal/g, -2,830,000 J/kg
Freezing: +79.7 cal/g, +330,000 J/kg
Condensation: +597.3 cal/g, +2,500,000 J/kg
Deposition: +677.0 cal/g, +2,830,000 J/kg
Note that melting and freezing have the same value except the latent heat is flowing in  an opposite direction. The same is true for the pairs of evaporation and condensation as  well as sublimation and deposition. Also note that the addition of melting and evaporation  is the value of sublimation as well as the addition of freezing and condensation  is the value of deposition. Note  that the magnitude of melting and freezing are much less than the other latent heat  processes. Thus melting and freezing do not contribute to cooling and warming the air  as much as the other processes. For example, 7.5 times as much cooling occurs from  evaporation than it does from melting.
These processes contribute to cooling and warming the air in the troposphere. Below is an  example for each:
Melting: Snow melting in the air as it falls (cools air)
Evaporation: Rain evaporating into the air and from the ground when and after it falls (cools air)
Sublimation: Surface snow vaporizing from the ground while temperature is still below freezing (cools air)
Freezing: Liquid cloud droplets being lifted into a very cold subfreezing layer in which they freeze (warms air)
Condensation: Liquid cloud developing as air rising by positive buoyancy (warms air)
Deposition: Frost developing on the ground when temperature is below freezing (warms air)
note: warming the air does not always mean an actual increase in temperature but could be a  reduction in the amount of cooling. In other words, the latent heat warming is partially offsetting some of  the cooling that would take place by another process (i.e. condensation warming partially offsetting  adiabatic cooling in a rising saturated air parcel). For a more detailed discussion of the  latent heat impact on weather forecasting see the Haby Hints below: