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 Precipitation - any form of water that falls from a cloud.
 Water vapor makes up only 0-4 % of the volume of air.
 3 phases or states of matter(s,l,g)
 6 phase changes - (f&m, e&c, s&d)

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Changing state requires that energy is transferred in the form of heat.
Latent Heat=“hidden heat” READ
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Evaporation is a cooling process.
Energy must be absorbed …(pool, sweat, energy comes from skin)
 Condensation energy must be released
 violent storms - energy from warm tropical waters.

 Saturated - air can NOT hold any more water vapor
 Warm air can hold more water vapor than cold air.
 Relative Humidity - ratio of the actual amount of water vapor to how much it can hold at that temperature.

 How to change relative humidity…
 1. Changed by adding or removing water vapor
 2. Change the temperature.
 Lowering air temperature causes an increase in relative humidity.
 Raising air temperature causes a decrease in relative humidity.

 Dew Point - temperature to which air must be cooled to reach saturation or condensation (fog, clouds).
 2 instruments used to measure humidity
1. Hair Hygrometer – uses a hair!
2. Sling Psychrometer - 2 bulbs (one dry one wet)

 High dew point temperatures indicate moist air.
 Low dew point temperatures indicate dry air.
 When the dew point is at or near the actual surface temperature expect humid, cloudy, or foggy conditions.

 Saturation occurs when water vapor is added to air or air is cooled.
 Compressed air warms.
 Expanded air cools.
 Adiabatic Temp. Changes —occur when air is compressed or expanded.

 1. Orographic lifting = mountains
 2. Frontal Wedging = at fronts the warm air rises over the cooler air.
 3. Convergence = two air masses meet and the result is air rising.
 4. Localized Lifting = warmer pockets of air over parking lots etc. rise

 Stable air (similar temperature top & bottom) does not rise too much thus few or no clouds.
 Unstable air (warmer temperatures at bottom compared to air at top) air rises thus clouds & possibly thunderstorms.
 Radiosonde = weather balloon.
 Temperature Inversions = read it!
(flipped)

 Cirrus - (curl of hair) - high, thin, wispy, made of ice. (front approaching)
 Cumulus - (pile/heap) - cauliflower, puffy, smaller ones - fair weather, larger
& darker - thunderstorms.
 Stratus - (layered) - sheets, steady rain to overcast conditions.

 Nimbus - rain clouds(dark gray)
 HIGH - cirro - icy, smaller, thinner
 MIDDLE - alto - medium sized
 LOW - larger
 Vertical Developed Clouds - low to high severe thunder/anvil/cumulonimbus

 Lenticular=lens shaped over mountains
 Heimholtz Waves=uh looks like waves
 Contrails=exhaust of of jets
 Mammatus=light bulb looking clouds
 Anvil Head=cumulonimbus – vertically developed thunder clouds
 Jomammatus=just kidding!

 Fog forms from either cooling or evaporation.
 How precipitation forms? (read about it)
 Pages 520-521
 Types of precipitation - snow, sleet, hail, glaze or freezing rain, and rain

1. Warmer air rises .
2. As it gets higher it cools down .
3. As it cools down it reaches its dew point (because cool air can’t hold as much water vapor).
4. Air at its dew point is saturated .
5. Saturated air condenses into water droplets (and they make up clouds).