CH 18 Moisture, CH 18 Moisture, Clouds, and Clouds, and PrecipitationPrecipitation

The States of WaterThe States of Water Evaporation And Evaporation And

HumidityHumidity States of waterStates of water

• solid-solid- ice, hail, ice, hail, snowsnow

• liquid-liquid- rain rain

• gas-gas- water water vapor, steamvapor, steam

Lake Lure and the Water Cycle

Water evaporates from the Lake into the air.In the air, the water vapor condenses into clouds.As more evaporation occurs, more clouds form.The clouds become saturated with water.When the clouds can hold no more water, they release it as precipitation.

EvaporationEvaporationEvaporationEvaporation

water molecules with enough water molecules with enough energy escape the water's surfaceenergy escape the water's surface

aa cooling processcooling process

When you sweat, water evaporates from your body and you are cooled.

HumidityHumidity a measure of the amount of moisture in a measure of the amount of moisture in

the airthe air specific humidityspecific humidity--the amount of water the amount of water

vapor actually present in the airvapor actually present in the air when specific humidity = air's capacity when specific humidity = air's capacity

for holding water vapor for holding water vapor air is air is saturatedsaturated

HumidityHumidity

Relative humidityRelative humidity expressed as a %expressed as a % amount of water amount of water

moisture the air moisture the air presently holdspresently holds

compared to the compared to the amount of water amount of water moisture it could hold moisture it could hold at same temperatureat same temperature

http://www.brainpop.com/science/weather/humidity/

100% = almost raining!

100% = almost raining!

Tropical Rainforest

= 80% or moreTropical Rainforest

= 80% or more

Desert = 25% or less

Desert = 25% or less

Rutherfordton Avg

= 45% - 89%Rutherfordton Avg

= 45% - 89%

How Does CondensationHow Does Condensation Happen?Happen? Air Temperature Reaches Air Temperature Reaches

the Dew Pointthe Dew Point Dew PointDew Point - temperature at - temperature at

which saturation occurs which saturation occurs 4 Ways that air loses heat4 Ways that air loses heat

• contacting a colder contacting a colder surfacesurface

• radiating heatradiating heat• mixing with colder airmixing with colder air• expanding when risesexpanding when rises

Water needs to condense Water needs to condense onon something something• condensation nucleicondensation nuclei

SaltSalt sulfate or nitrate particles (pollution)sulfate or nitrate particles (pollution)

• puff of smoke contains millions of particlespuff of smoke contains millions of particles

http://explore.ecb.org/videos/VLC_media?P1=VLC035&REFERER=OTHER

F/A 18 forces condensation out of the air approaching the speed of sound

CloudCloudss

CloudsClouds high fogs, mist, or haze high fogs, mist, or haze

that form when air above that form when air above the surface cools below the surface cools below its dew pointits dew point

Three main cloud typesThree main cloud types CirrusCirrus

• thin feathery or tufted thin feathery or tufted high ice-crystal cloudshigh ice-crystal clouds

StratusStratus• low sheets or layers, low sheets or layers,

form in stable airform in stable air (moving upward (moving upward slowly)slowly)

CumulusCumulus• thick fleecy masses thick fleecy masses

formed by formed by verticallyvertically risingrising air currents air currents

Cloud TypesCloud Types

Clouds are classified into a system that uses Clouds are classified into a system that uses Latin words to describe the appearance of Latin words to describe the appearance of clouds as seen by an observer on the ground. clouds as seen by an observer on the ground.

Latin RootLatin Root TranslationTranslation ExampleExample

cumulus cumulus heap heap cumuluscumulus

StratusStratus layer layer altostratus altostratus cirruscirrus curl of hair curl of hair cirrus cirrus nimbus nimbus rainraincumulonimbuscumulonimbus

Types of CloudsTypes of Clouds

Cumulonimbus

Cumulonimbus w/wall cloud

Supercell Storms

http://dsc.discovery.com/videos/storm-chasers-science-of-storm-chasing/

http://www.weather.com/multimedia/videoplayer.html?from=email&bcpid=823503751&bclid=1716487196&bctid=1735125381

Forms of PrecipitationForms of Precipitation

RainRain – liquid from – liquid from stratus / cumulus stratus / cumulus cloudsclouds

HailHail – frozen clumps – frozen clumps of ice crystals from of ice crystals from cumulonimbuscumulonimbus

SleetSleet – raindrops that – raindrops that freeze on their way freeze on their way downdown

SnowSnow – solid particles – solid particles from stratus / cumulus from stratus / cumulus cloudsclouds

RainRain

House washes awayhttp://www.weather.com/multimedia/videoplayer.html?from=email&bcpid=823425597&bclid=16267856001&bctid=16749162001

Kite Surfer Slams into Buildinghttp://www.weather.com/multimedia/videoplayer.html?from=email&bcpid=823425597&bclid=16267856001&bctid=16749161001

Hurricane Ike at nighthttp://www.weather.com/multimedia/videoplayer.html?from=email&bcpid=823425597&bclid=16267856001&bctid=16749157001

SnowSnow

Thunder Snow http://www.weather.com/multimedia/videoplayer.html?from=email&bcpid=823425597&bclid=1544345027&bctid=1543272495

Snowboundhttp://www.weather.com/multimedia/videoplayer.html?from=email&bcpid=823503751&bclid=861985479&bctid=877032736

Snowflake manhttp://www.weather.com/multimedia/videoplayer.html?from=email&bcpid=823503751&bclid=861985479&bctid=877032737

Sleet and IceSleet and IceBlack Ice vs. Sleet http://www.weather.com/multimedia/videoplayer.html?from=email&bcpid=823503751&bclid=1716487196&bctid=1797103527

MSN Ice Storm in Midwest http://video.msn.com/video.aspx/?mkt=en-US&brand=msnbc&vid=1a768a27-b151-4d11-93e9-8af0158dd0e5&wa=wsignin1.0

HailHail

http://www.weather.com/multimedia/videoplayer.html?from=email&bcpid=823425597&bclid=1164702865&bctid=33526267001

http://www.weather.com/multimedia/videoplayer.html?from=email&bcpid=823425597&bclid=1164702865&bctid=32425805001

Where it Rains…Where it Rains…

Pacific NorthwestPacific Northwest

Precipitation AreasPrecipitation Areas

Where it RainsWhere it Rains windwardwindward side of side of

mountain rangesmountain ranges storm areas, places storm areas, places

wherewhere air rises and air rises and coolscools

areas favored by areas favored by global wind beltsglobal wind belts

• where air where air convergesconverges and has to go up…. and has to go up…. around the Equatoraround the Equator

Where it Doesn’tWhere it Doesn’t leewardleeward side of side of

mountain rangesmountain ranges areas ofareas of sinking sinking

(warming) air(warming) air high pressure areashigh pressure areas where global wind where global wind

belts belts divergediverge

Acid RainAcid Rain

Sulfate (Sulfate (SOSO22) ) andand Nitrate (Nitrate (NONO22))particles particles from pollution act as from pollution act as condensation nucleicondensation nuclei from burning of fossil from burning of fossil

fuels, volcanoes, and fuels, volcanoes, and automobilesautomobiles

Effects of Acid RainEffects of Acid Rain

Avalanche Lake in Avalanche Lake in Adirondack Park, Adirondack Park, New York State. New York State. Watersheds are Watersheds are especially vulnerable especially vulnerable to acid rain to acid rain

Vermont's maple Vermont's maple trees are particularly trees are particularly susceptible to the susceptible to the effects of acid rain effects of acid rain