Evaporation, Condensation, Clouds and Precipitation

Water exists as a solid, liquid, and gas can change from one state to another The change from a solid to a liquid is called melting, liquid to a solid is called freezing Heat of Fusion = +/- 334 J/g/°C

GAS LIQUID SOLID

Evaporation the process of water changing from a liquid to a gas occurs when water absorbs energy from its surroundings Because of this, evaporation results in the surroundings becoming cooler (think of sweating) Heat of Vaporization = 2260 J/g

EVAPORATION IS A COOLING PROCESS

Condensation the process of water changing from a gas to a liquid occurs when water vapor loses energy Because of this, condensation results in the surroundings getting warmer Heat of Vaporization = -2260 J/g

COOL TEMPS - CONDENSATION WARM TEMPERATURE - EVAPORATION

CONDENSATION IS A WARMING PROCESS

Clouds formed by the condensation of water vapor There are three main types of clouds: cumulus, stratus, and cirrus Cumulus clouds are thick, puffy clouds. They tend to be lower in the sky Stratus clouds appear as low to middle sheets or layers of clouds Cirrus clouds appear as high, thin or “feathery” clouds. These clouds are made of ice crystals There are many forms of these types of clouds Ex. Cumulonimbus clouds often produce strong thunderstorms and can form tornadoes!! Nimbus – rain/storm in Latin

CLOUDS have FLAT BOTTOMS which indicate the level of the atmosphere where the dew point temperature has been reached!

Cumulus clouds are "fair weather" clouds and are unlikely to produce precipitation They form in warm air on sunny days Cumulus clouds can form at almost any altitude, with bases sometimes as high as 14,000 feet

Cumulus clouds are clouds of vertical development and may grow upwards dramatically under certain circumstances The updrafts may be caused by heating of the air by the ground surface, the action of a cold front, or to temperature differences between land and ocean The vertical air currents results in towering clouds with an anvil head on top called cumulonimbus clouds

Stratus clouds are low clouds, ranging in height from near the earth's surface up to 6,500 feet Stratus clouds form flat layers or uniform sheets Only a fine drizzle can form from stratus clouds because there is no vertical development

Cirrus clouds are wispy in appearance, and resemble horsetails (they are sometimes called mares' tails) They are among the highest clouds, forming at elevations of 25,000 feet and above, where the temperatures are far below freezing Cirrus clouds are formed almost entirely of tiny ice crystals

Precipitation any form of water that falls from the clouds when they become too large be supported by the air Forms of precipitation include: Rain Snow Sleet – rain that falls through air that is below freezing Freezing rain – rain that freezes on contact with a surface that is below freezing Hail – formed in cumulonimbus clouds (thunderstorms). These are ice balls which can be as large as a softball!! HAIL USUALLY HAPPENS IN THE SUMMERTIME!! **When water condenses on nitrate and sulfate particles (from burning fossil fuels), acid rain is formed

Hail Formation

Supercooled Rain Level Snow Level Ice Level Supercooled Rain Level BRRRR…I’m CHILLY! Rain Level

Precipitation does not occur the same everywhere (OROGRAPHIC LIFT) Wind hits the windward side of the mountain, rises, cools off, and condensation happens This forms clouds and precipitation As the air goes over the top, is sinks on the leeward side As the air sinks, it compresses together and gets warmed by friction Since the warmer air can hold more moisture, condensation does not occur (and no precipitation)! Occurs along the Sierra Nevada Mts. The California side is wet, the Nevada side is dry