Air Masses Large bodies of air formed when a body of air hangs over a region and takes the temperature and humidity from that region

4 types 1. Continental polar cold and dry effects Michigan the most 2. Maritime polar cold and moist

3. Continental Tropic warm and dry 4. Maritime Tropic warm and moist effects Florida

FRONTS Boundary between two air masses 4 types: 1. cold 2. warm 3. stationary 4. occluded

COLD FRONT Cold air mass pushes a warm air mass steep slope brings thunderstorms or severe weather Cumulonimbus clouds

WARM FRONT Warm air mass pushes a weaker cold air mass little temperature change brings steady rain stratus clouds

STATIONARY FRONT When two air masses meet but cannot push each other steady rain for days

OCCLUDED FRONT A cold front overtakes a warm front warm air forced up rapidly LOW pressure and storms L

Causes of wind 1. Uneven heating of the Earth creates: 2. Differences in air pressure creates: High pressure area and low pressure area All winds blow from a High pressure to a Low pressure

Works with other things too!!

Clicker What caused the can to crush? a)Increased external air pressure b)Decreased external air pressure c)Water vapor condensing d)Liquid water evaporating

3. CONVECTION CELLS Warm air rises; cool air sinks

4. CORIOLIS EFFECT Caused by the rotation of the earth Earth rotates on the average 750mph – faster at the equator –Causes winds to be deflected to the right in the –Northern Hemisphere

Coriolis Force clockwise rotation, the deflection is to the left of the motion of the object; in one with counter-clockwise rotation, the deflection is to the right. WESTERLIES Blows from the west to the east Effects the weather the most in the US TRADE WINDS OR EASTERLIES Blow from the east toward the equator

Clicker Which way do winds blow? a)From high pressure to low pressure b)East to north c)Low pressure to high pressure d)South to East

Isobars- line that connect areas of equal air pressure

Instruments 1.Anemometer- measures wind speed 2.Wind Vane- measures wind direction

Isobars and relative wind speed Close isobars=high wind speed Low Pressure System: Increased cloudiness, winds, temperatures, and chance of precipitation. High Pressure System: Indicates clear, calm conditions with reduced chance of precipitation.

Cumulonimbus clouds -Contain heavy rain, lightning, hail and wind -Possible tornadoes -Associated with a cold front Two of the most important ingredients for thunderstorm formation are instability (unstable air) and moisture.

 During a thunderstorm, the Earth's surface has a positive charge. Because opposites attract, the negative charge at the bottom of the thunder cloud wants to link up with the positive charge of the Earth's surface.

 1. The electricity passes through the air and starts it vibrating. The vibrations cause sound.  2. The lightning is also very hot and heats up the air around it. Hot air expands and the air gets bigger very quickly, and pushes apart the air particles.  These vibrations are what you hear and call thunder

THUNDERSTORM DOWNBURST

 Form at the base of a cumulonimbus cloud  The formation of tornadoes is the result of warm, moist air meeting cooler, dry air, and creating instability in the atmosphere.  Season: spring to mid-summer  Strongest wind speeds  Ranked on the (Enhanced) Fujita Scale

FUJITA SCALE EF-0 EF-1 EF mph mph mph

EF-3 EF mph mph

EF-5 Over 200 mph

 Cyclone over warm water  Pre-existing storm  Has an eye – low pressure in the center

 Has a storm surge-  Most dangerous part of a hurricane  Wall of water near the eye  Causes most destruction and loss of life

ANDREW-1992

Hurricane season June 1- Nov.30  Tropical DepressionWind speeds between 20 and 34 knots (23-39 mi/hr)  Tropical StormWind speeds between 35 and 64 knots (40-73 mi/hr)  HurricaneWind speed greater than 64 knots (74 mi/hr)

 Rotation : Clockwise or Counter clockwise ?  Counter clockwise  The eye is the center of the storm.  The eye wall surrounds the eye. The strongest winds and heaviest rains are found in the eye wall.  Rain bands are long, arching bands of clouds and thunderstorms that spiral out from the eye wall.

 Hurricane season June 1- Nov.30

 if it moves over land, thus depriving it of the warm water it needs to power itself, quickly losing strength.

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