Water and Weather

Weather and WaterMost weather we pay attention to

involves water

http://blogs.reuters.com/wp-content/uploads/2007/07/storm1.jpg http://img.dailymail.co.uk/i/pix/2008/04_01/tornadoDM3030d_468x312.jpg

http://img.dailymail.co.uk/i/pix/2008/04_01/tornadoDM3030a_800x533.jpg

Important TermsHumidity – amount of water

vapor in the airRelative Humidity - ratio of

water vapor in an area relative to how much it can holdwarm air can hold more

water than cold air before becoming saturated – can hold no more water vapor

(pressure also a factor)Expressed as a %Does not tell you actual

quantity of water vapor in air

http://wpcontent.answers.com/wikipedia/en/4/41/Relative_Humidity.png

Important Terms

http://fuffer.files.wordpress.com/2008/03/humidity-smaller.jpg

Important TermsDew Point – temperature air must be cooled at

to reach saturation (100% relative humidity)High dew point temps = moist airLow dew point temps = dry air

At the dew point water vapor can condenseat night low temps near ground cause water

vapor to condense dew/fogvery cold temps near ground cause water vapor

to freeze and fall out frostduring the day, as warm air rises, it cools and

often becomes saturated clouds

Dew Point

Mean daily average dew point temperature in Octoberhttp://www.climatesource.com/us/fact_sheets/td_us.gif

Cloud FormationClouds form as warm, moist

air rises, expands, and coolsAs air cools, it can hold less

water – relative humidity increases

When air reaches dew point (100% relative humidity), the water condenses (goes from gas to liquid) around a piece of dust, sea salt, or other particle (condensation nuclei)

When millions of water droplets collect, cloud is formed

http://www.cmmap.org/images/learn/clouds/sfcHeat.jpg

Cloud Formation

http://www.vivoscuola.it/US/RSIGPP3202/umidita/lezioni/formation2.GIF

http://www.weatherquestions.com/Cloud_formation_convective.gif

Cloud FormationMay also form when wind hits a mountain and has

nowhere to go but up air rises, expands, and coolsCan also form when air masses of different temps

collide warmer air is forced up above cool air mass where it expands and cools

http://www.cmmap.org/images/learn/clouds/risingAir.jpg

Cloud FormationTypes of cloud form:

at different altitudes High Middle Low

into different shapes Cirrus Cumulus Stratus

Make Clouds labBuild Cloud SpottersMonitor clouds for 1

weekhttp://marktwainmediascience.com/CD-410015.jpg

PrecipitationCloud droplets

collide and combine into bigger droplets (coalescence)

When droplets are too heavy, they fall (precipitation)

May fall as liquid or solid or something in between (rain, snow, sleet, hail)

http://www.mmm.ucar.edu/research_mmm/processes/images/ice_illustration.png

PrecipitationHow does water get

in the air in the first place?Evaporation

radiation heats up water and causes phase change

Warm surface water (oceans) evaporates faster than cold

http://www.cotf.edu/ete/images/modules/msese/earthsysflr/EFCycleP3.gif