1.  1. Which layer of the atmosphere has the coldest temperatures?  2. In which layer/s do we fly airplanes?  3. How does pressure change as elevation increases?  4.How does temperature change as elevation increases?  5. What is the difference between temperature and heat?

3. Air pressure is the pressure exerted by the weight of air above Exerted in all directions (up, down, and sideways) The air pressure pushing down on an object exactly balances the air pressure pushing up on the object Average Air Pressure at sea level is: 1 kg/cm 2 = 1013.2 mb = 1 atm = 29.92 in. of mercury

5.  Barometer: device used for measuring air pressure  Unit:  millibars (mb)  inches of mercury (in. Hg)  Atmospheres (atm.)  Torricelli: invented the mercury barometer in 1643

6. Types of barometers Mercury When air pressure increases, the mercury in the tube rises When air pressure decreases, the mercury in the tube goes down Aneroid recording mechanism providing a continuous record of pressure change over time

7.  Wind is a result of horizontal differences in air pressure  Air flows from areas of high pressure to areas of lower pressure.

8. The unequal heating of earth’s surface generates pressure differences Solar radiation is the ultimate energy source for most wind

9.  Pressure Differences  Coriolis Effect  Friction

10.  Isobars  Show lines on a map that connect places of equal air pressure  A pressure gradient  The spacing of isobars indicates the amount of pressure change over a given time

11.  Closely spaced isobars: indicate a steep pressure gradient and high winds.  Widely spaced isobars: indicate a weak pressure gradient and light winds.

13.  The Coriolis effect describes how Earth’s rotation affects moving objects.  Northern Hemisphere  Deflected to right,  Moves counterclockwise  Southern Hemisphere  Deflected to the left,  Moves clockwise

14. © Important only within a few km of Earth’s surface © Acts to slow air movement, which changes wind direction © Friction is at its highest in mountains.

15. © Jet streams are fast-moving rivers of air © Speed: 120 and 240 kilometers per hour © Direction: West- to-east direction.

16. Low Pressure Centers High Pressure Centers Centers ofLow PressureHigh Pressure AKACyclonesAnti-cylones Pressure Behavior Pressure decreases from the outer isobars towards the center The values of the isobars increase from the outside towards the center Wind BehaviorWinds blow inward and counterclockwise Winds blow outward and clockwise Weather Associated Severe and stormyFair and Sunny Symbol“L” that is RED“H” that is BLUE

18.  The atmosphere balances itself by acting as a giant heat-transferring system  Moves warm air to the poles and cool air towards the equator

19.  Equatorial Low  A region characterized by abundant precipitation and rising air  Trade winds  Two belts of winds that blow almost constantly from east to west  Subtropical High  Area of sinking air at 30˚north or south latitude

20.  Westerlies  Dominate west to east motion of the atmosphere (Jet Stream occurs here)  Subpolar Low  Rising air area  Polar easterlies  Winds that blow east to west  Polar High  Sinking air area  Polar front  Interaction of warm and cool air masses produces a stormy belt

21.  Small scale winds produced by a locally generated pressure gradients  Types of Local Winds  Land Breezes  Sea Breezes  Valley Breezes  Mountain Breezes

22.  Sea Breezes  Day – air above the land heats, expands, and rises (area of lower pressure)  Cooler air over water moves towards the warmer land  Strongest in mid-afternoon Land Breezes Night – air above the land quickly cools off The cooler air over land moves to the warmer sea air Known as the “Lake Effect”

23. V alley Day – heating during the day generates warm air that rises from the valley floor. “Upslope Breezes” Mountain Night –cooling of the air near mountain slopes results in cool air moving into the valley “Down-slope Breezes” Ex. Grand Canyon at night

24.  Direction  Labeled by the direction from which they blow  Tool: Wind Vane

25.  Anemometer  Measures how fast wind is blowing