The Hydrologic Cycle  The basic hydrologic (or water) cycleThe
hydrologic cycle involves the continuous circulation of water in
the Earth-Atmosphere system. At its core, the water cycle is the
motion of the water from the ground to the atmosphere and back
again. Of the many processes involved in the hydrologic cycle,
the most important are...    • evaporation   • transpiration   •
condensation   • precipitation   • runoff  Evaporation is the
change of state in a substance from a liquid to a gas. In
meteorology, the substance we are concerned about the most is
water.  For evaporation to take place, energy is required. The
energy can come from any source: the sun, the atmosphere, the
earth, or objects on the earth such as humans.  Everyone has
experienced evaporation personally. When the body heats up due
to the air temperature or through exercise, the body sweats,
secreting water onto the skin.  The purpose is to cause the body
to use its heat to evaporate the liquid, thereby removing heat
and cooling the body