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ATMOSPHERE Layers of the Atmosphere Air pressure Heat Transfer in the Atmosphere Winds and Air Movement Moisture in the Atmosphere Composition of the Atmosphere What gases are found in a normal volume of breathable air? What is air? – – – – – – Nitrogen Oxygen Carbon Dioxide .03% Argon .9% Water Vapor 1-4% Other trace gases Layers of the Atmosphere Troposphere Stratosphere Mesosphere Thermosphere Ionosphere Exosphere The Layers in Relation to the Earth Uneven Heating of the Earth Convection & Winds How the Sun Strikes the Earth Cause of uneven Heating of earth – Earth’s Tilt – A Sphere cannot receive direct sunlight evenly everywhere http://esminfo.prenhall.com/ science/geoanimations/anim ations/01_EarthSun_E2.htm l Global Winds •Winds that affect the entire globe •Caused by the Rotation of the Earth •Influenced by local geology/landforms/elevations Three Major Wind Belts in Each Hemisphere Easterlies Westerlies Tradewinds Pressure Belts Associated With Winds Pressure Belts Air moves from high to low pressure Cold air at the poles sinks Warm air at the equator rises The Pressure belts are divided up by these basic movements of air Local Winds How local surroundings affect breezes and winds Local Winds Caused by the unique conditions in each location Depends on landscape, elevation, latitude, and nearness to bodies of water Major Types: – – – – – – Land Breeze Sea Breeze Mountain Breeze Valley Breeze Thermals Wind Shear Sea Breeze Most closely associated with the daily heating of the earth and the nightly cooling of earth Land Breeze Mountain Breeze Vs. Valley Breeze Primarily a result of density – cold air sinks and warm air rises Day and Night affect this flow Thermals Thermals Thermals are updrafts of warm air that rise from the ground into the sky. http://www.aerospaceweb.org/question/nature/ q0253.shtml Wind Shear Wind shear is defined as a change in wind speed and/or direction within a short distance. It can be in either a horizontal or vertical direction, or both. This change causes a shearing or tearing effect, which causes great concern for pilots and airline industries. Air Masses Characteristics How we name them The Weather they cause Air Masses An air mass is a large body of air with generally uniform temperature and humidity. The area from which an air mass originates is called a "source region." Characteristics of Air Masses Cold and Dry Cold and Moist Warm and Dry Warm and Moist Jet Stream Naming Air Masses Continental arctic Continental polar Continental tropical Maritime arctic Maritime polar Maritime tropical How Air Masses are formed and named. Air Masses are named for the area over which they form. Example: the air over a tropical ocean would be _______ & ____________. Air Masses that affect North America mP * mT cP * cT c = continental T = tropical P = Polar m= Maritime(ocean) Typical Air Mass Movement Air Mass Location Practice Fronts Fronts are the boundaries between air masses of different temperature. If warm air is moving toward cold air, it is a “warm front”. If cold air is moving toward warm air, then it is a “cold front Types of Fronts Cold Front Warm Front Occluded Front Stationary Front Fronts are associated with changes in weather Cold Front Cold fronts occur when heavy cold air displaces lighter warm air, pushing it upward. Cumulus clouds form and usually grow into thunderstorms. Temperatures drop anywhere from 5 degrees to 15. Winds become gusty and erratic. Rain, snow, sleet, and hail can occur with a cold front. Warm Front A warm front is defined as the transition zone where a warm air mass is replacing a cold air mass. Warm fronts generally move from southwest to northeast and the air behind a warm front is warmer and more moist than the air ahead of it. When a warm front passes through, the air becomes noticeably warmer and more humid than it was before Occluded Front Occluded fronts occur when cold air is replacing cool air or vice versa at the surface, with warm air above. A cold occlusion occurs when cold air shoves its way under cool air at the surface. Warm air aloft is usually to the west of the surface front. A warm occlusion occurs when cool air rises over cold air. The warm-cold air boundary is often east of the surface front. Both types of fronts are usually associated with rain or snow and cumulus clouds. Temperature fluctuations are small and winds are gentle Stationary Front Stationary fronts occur when neither warm nor cold air advances. The two air masses reach a stalemate. These type of conditions can last for days, producing nothing but Altocumulus clouds. Temperatures remain stagnant and winds are gentle to nil. Cyclone/Anti Cyclone Coriolis Effect http://www.classzone. com/books/earth_scien ce/terc/content/visuali zations/es1904/es1904 page01.cfm?chapter_n o=visualization