Precipitation

Types of Precipitation Rain Snow Dew Frost Hail

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

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

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

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

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

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

Convectional Precipitation (summer thunderstorm)

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)

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.