1. Evaporation is a water phase change in which more water molecules enter
the atmosphere than return as liquid at the interface of liquid water and air.
The result is a net loss in liquid water mass.
Transpiration is a water phase change where water taken up from the soil
by plant roots eventually escapes to the atmosphere as vapor through tiny
pores on the surface of green leaves.
Condensation is the water phase change that happens at the interface of
liquid water and air where more water molecules return to the water surface
as liquid than enter the atmosphere as vapor. The result is then a net gain of
liquid water mass.
Deposition occurs when water vapor becomes ice without first becoming liquid.
If more atmospheric water molecules transition to ice than go from ice to
vapor, a net gain of ice mass occurs.
Sublimation is when ice and air (such as surface of snow cover) interface and
there are more water molecules entering the atmosphere as vapor than changing to
ice, causing a net loss of ice mass.
2. Heat energy affects the change of phases of water due to the slowing (with less
heat energy) or the speeding up (with more heat energy) of the movement of
water molecules. For evaporation, transpiration or sublimation, more heat causes
the water molecules to move faster, causing the release of kinetic energy and then
more water vapor to escape to the atmosphere. With slower moving molecules,
water vapor either condenses or deposition occurs.
3. Air pressure is the total amount of force that is exerted on a surface by all
the molecules composing air – both gas and water. Vapor pressure is the
