1. Precipitation

2. Types of Precipitation
Rain
Snow
Dew
Frost
Hail

3. Facts about air we need to know
Warm air is lighter than cold air
Warm air holds more moisture than cold air
Water holds heat longer than land
Air cools as it rises
When air passes over water, it picks up moisture

4. Reasons why air may rise
It is forced up by relief (mountains)
It absorbs heat from the earth’s surface
It is pushed up by a cooler denser (heavier) air mass

5. Air Pressure Air has weight = air pressure Low Pressure High Pressure
Warm air rising
Bad weather
High Pressure
Cold air falls towards the earth
Good Weather
When a pressure goes from High to Low = STORM

6. Types of Precipitation Storms
1. Relief (Mountain)
2. Convectional (absorbed heat)
3. Cyclonic (Frontal)

7. Relief Precipitation
As moist warm air rises up the mountain, it expands and cools
As the air cools, the rate of evaporation decreases but the rate of condensation increases.
As more water condenses, the clouds become larger
When the clouds are too heavy, they release precipitation to the ground

8. Windward vs Leeward
Windward Leeward
Side (wet) Side (dry)

9. Convectional Precipitation (summer thunderstorm)

10. Cyclonic Precipitation
Definition
A large low pressure system that forms when a warm air mass and a cold air mass collide.
Occurs when the Polar-Front Jet stream (cold, dry air) collides with the warm tropical air of the Gulf of Mexico (warm & moist air)

11. Cyclonic Precipitation (aka Battle of the sky)
Cold, dense (heavy) air mass hits less dense warm moist air, forcing it up
As air mass rises, it cools and condenses to form clouds and precipitation.
Moisture falls through cold air below to cool the earth’s surface.