Weather is the of the Earth s atmosphere at a place and time. It is the movement of through the atmosphere o Energy comes from the

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1 Weather Notes Weather Weather is the of the Earth s atmosphere at a place and time It is the movement of through the atmosphere o Energy comes from the The sun is the force that weather The sun s energy with earth s atmosphere in the atmosphere o 50 % by earth s surface. This heats the land and water o Some absorbed energy is back to the atmosphere. As infrared radiation o 5% is by the surface back into the atmosphere o 20% is absorbed by and particles in the atmosphere o 25% of incoming sun is by dust, clouds, & particles Heat Transfer Conduction: direct from one substance to another (touching) Radiation: direct transfer of by electromagnetic waves (through space) Convection: transfer of heat by the movement of (liquid or gas) Wind Wind is the movement of air from an area of pressure to an area of pressure pressure Low

2 Difference in pressure o Caused by the heating of the atmosphere The air (by equator) rises The cool air or rushes to replace the rising air Measure wind o Use anemometer unit of m.p.h. (miles per hour) Wind chill: the blowing of wind on your skin makes you feel Local Winds Local winds: winds that over a small area Caused by unequal heating in a area o Examples Sea Breeze: cool air blows from toward land where hotter air has risen Land Breeze: land cools than body of water at night Hot air over water and rises air from land rushes in over the water Global winds Global winds: winds that are caused by unequal heating of the o Occurs over areas o Form from giant currents in the atmosphere (Hot up, Cold down) Air pressure at the poles is than air pressure at the equator *PRESSURE DIFFERENCE CAUSES WIND* o Coriolis Effect: global winds due to the rotation of the earth. The Coriolis effect is the way the earth s makes the wind curve Winds in North curve toward equator Winds in curve left toward equator Calm Areas o Doldrums: area near the The hot air rises and is replaced by cold air, but the cold air is heated so there is not much horizontal movement o Horse latitudes: occur at 30 o North and South of equator Cool air sinks: very area

3 Global wind Belts o Trade winds: blow from the horse latitudes toward the Used for routes o Polar easterlies: Cold air near the poles sinks and back toward the lower latitudes Coriolis effect these winds so they meet prevailing westerlies Creates the front o Prevailing westerlies: occur in the mid-latitudes (30 o -60 o N & S) These blow towards the Very important to in the USA Jet Stream: bands of high speed air 10 km the earth ( km/hr) o Blow from West to East Water in the Atmosphere Humidity Humidity: is a measure of the in the air o Warm air can hold H 2 O vapor than cool air Relative Humidity: The amount of water vapor the air can hold at a particular time Dew Point: The temperature where condensation o When water vapor to liquid water Clouds Clouds form when water vapor in the air to form liquid water or ice crystals o Condensation occurs when the changes and has small particles to rest on Dew: condensation on a Frost: condensation on a surface at a Temperature below Three main types of clouds o Classified by their o Cirrus: wispy hooked ends only at altitude made of crystals is coming

4 o Cumulus: white Some indicate weather others indicate (cumulonimbus) nimbus means o Stratus: flat layers can produce, rain or snow called nimbostratus o Altocumulus and Altostratus: clouds o Fog: cloud that forms on or near Air Masses and Fronts Air Mass Air Mass is a huge body of air that has temperature, humidity and air pressure. There are 4 air masses Classified by the and content o Polar: Form north of the 50 o N. Latitude or South of 50 o S. Latitude air pressure o Tropical: air pressure Maritime form in the (wet) o Maritime: Tropical Maritime Forms over (Warm) o Continental: air forms over Polar (Cold) Polar Continental (dry) Tropical Continental Air masses move 2 ways o Streams o Prevailing Front Front: the boundary where air masses Four types of fronts Cold Front: moving o Can have thunderstorms o heavy cold air pushes lighter air upwards

5 Warm Front: moving o Precipitation o Warm air cold air by sliding over it Stationary Front: Cold air and warm air are at a o Precipitation can for days o warm nor cold air advances Occluded Front: Warm air is between 2 cool air fronts o Very complex o Precipitation o Cold air is cool air at the surface warm caught air above Cyclone and Anticyclone Cyclone: an area of pressure where wind spins counterclockwise o Area of Anticyclone: an area of pressure where wind spins clockwise o dry weather Storms Storms: disturbance in the atmosphere Thunderstorms They form in a cumulonimbus cloud o Thunderheads Form when warm air is forced during a cold front Form on & humid afternoons Storm Movement o Heavy o Strong within the cloud Lightening: particles travel between the cloud and earth

6 Tornadoes Tornado is a rapidly, funnel-shaped cloud that reaches the earth. Form most commonly in cumulonimbus clouds o Warm moist air from the bottom of the cloud flows (LOW PRESSURE IN CLOUD) Warm air begins to Tornado forms as the funnel Measuring Tornadoes o Fujita scale (F0-F5) Hurricanes Hurricane: tropical cyclone that has of 119 km/hr or higher Formation of Hurricane o Warm air rises around the eye in spiraling bands o Air flow near the top of the hurricane o Cool dry air in the eye Hurricanes form over ocean water o As low pressure area or depression Hurricanes move in the by the Easterly Trade Winds Storm Surge: a of water that sweeps across the coast where the hurricane lands.

7 Lake effect Snow: Cool dry air mass moves over a body of water and up water vapor Snow after the water vapor condenses again. Climate Scientists use two main factors precipitation and temperature to describe the of a region Factors affecting Temperature (distance from sea level) Distance from bodies of currents (distance from equator) o World Temperature Polar Zone: climates Temperate zone: warm or hot in, cool or cold in. Tropical zone: climate Factors affecting Precipitation Prevailing Seasonal