WATER IN THE ATMOSPHERE

WATER CYCLE  Water  Water is always moving between the atmosphere and Earth’s surface.  This  This movement is known as the water cycle.  3  3 major processes of the water cycle –Evaporation –Condensation –Precipitation

Evaporation  When liquid water changes into a gas.  This is also known as water vapor.  Water vapor usually comes from a body of water, such as, oceans, ponds, lakes, stream, or even puddles.

Humidity  The amount of water vapor in the air.  It can vary from place to place.  Air is saturated when the evaporation is equal to the condensation.

Relative humidity  It compares the amount of water vapor in the air with the maximum amount that it can hold.  50% RH is about ½ of the amount of water need for saturation.

Condensation  Water  Water vapor cools and condenses into liquid water.  These  These condensed water droplets clump together around tiny dust particles to form clouds.

Cumulus Clouds  Means  Means “heap or mass”  Forms  Forms less than 2 km above the ground and can extend 18km up.  Indicates  Indicates fair weather  Fluffy  Fluffy rounded piles  Cumulonimbus  Cumulonimbus – often produce thunderstorms.

STRATUS CLOUDS  Means “spread out”  Form flat layers  Cover all or most of the sky  As they thicken they may produce drizzle, rain, or snow

A cloud that rests on the ground or over a body of water.A cloud that rests on the ground or over a body of water. Forms when surface is colder than the air above it.Forms when surface is colder than the air above it. It clears as the ground is heated by the sun.It clears as the ground is heated by the sun. Fog

CIRRUS HHHHigh clouds WWWWispy and feathery MMMMade mostly of ice crystals CCCCirrocumulus: looks like a row of cotton balls OOOOften indicate a storm is on the way.

Precipitation  Water droplets that get heavy enough to fall to the Earth’s surface.  Forms of precipitation include: rain, snow, sleet, and hail.  Most water molecules spend about 10 days in the atmosphere.  Rain most common form of precipitation.  Snow is water vapor that freezes directly into ice crystals. The ice crystals will clump together and form snowflakes.  Sleet raindrops that freezes as they fall through the atmosphere.  Hail starts as an ice pellet, as it falls through the atmosphere is melts and refreezes forming a hailstone.

PRECIP. CONTINUE RRRRain needs to be at least.5mm in diameter FFFFreezing rain is rain that freezes when it hits the ground not in the air. PPPPrecipitation ALWAYS comes from clouds, but not ALL clouds produce precipitation.