1. (Discussion and Worksheet – Wind)
Wednesday April 11, 2018
(Discussion and Worksheet – Wind)

2. What causes wind in our atmosphere?
The Launch Pad
Wednesday, 4/11/18
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What causes wind in our atmosphere?
The Sun's energy warms the Earth's surface unevenly, creating pressure differences, and this causes the atmosphere to move as wind from higher pressure areas to areas of lower pressure.

3. We will take Quiz 15 on Friday!
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4. 3/29 N/A 4/6 4/9 4/10 Friday, 4/20 F5 F6 F7 F8 Assignment
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4/9
Video WS – Atmospheric Circulation F8
4/10
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5. Wind “Wind” is defined as the movement of air molecules.
Air moves out of areas of higher pressure into areas of lower pressure.
Unequal heating of Earth’s surface generates these pressure differences.
Solar radiation, therefore, is the ultimate energy source for most wind.
Wind is controlled by a combination of forces, including:
the pressure-gradient force
the Coriolis effect
friction

6. Isobars are lines that connect places of equal air pressure.
The spacing of isobars indicates the amount of pressure change over a given distance and is expressed as the “pressure gradient.”

7. The Coriolis effect is also a participant in controlling the wind.
This effect is an apparent deflection in the wind direction due to the Earth’s rotation.
Deflection of the wind is to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.

8. Finally, friction acts to slow the air’s movement near the surface.
Wind
Finally, friction acts to slow the air’s movement near the surface.

9. The Geostrophic Wind
Upper level winds generally blow parallel to isobars, and are called geostrophic winds.

10. The Geostrophic Wind
Figure 18.8

11. The Jet Stream
The Jet Stream is a “river” of air at high altitude with a velocity of 120–240 kilometers per hour.

12. Comparison of Upper-Level Winds and Surface Winds

13. Wind Speeds of Tropical Depressions and Tropical Storms
Tropical Depression A tropical depression is a tropical cyclone in which the maximum sustained wind speed is up to 33 kt (38 mph, 17 m/s). Depressions have a closed circulation.

14. Wind Speeds of Tropical Depressions and Tropical Storms
Tropical Storm A tropical storm is a tropical cyclone in which the maximum sustained surface wind speed ranges from 34 kt (39 mph,17.5 m/s) to 63 kt (73 mph, 32.5 m/s). The convection in tropical storms is usually more concentrated near the center with outer rainfall organizing into distinct bands.

15. Saffir-Simpson Hurricane Wind Scale

16. Category 1 Hurricanes
Category 1: Winds mph. Storm surge generally 4-5 feet above normal. No major damage to building structures. Damage primarily to unanchored mobile homes, shrubbery, and trees. Some damage to poorly constructed signs. Also, some coastal road flooding and minor pier damage.

17. Category 2 Hurricanes
Category 2: Winds mph. Storm surge generally 6-8 feet above normal. Some roofing material, door, and window damage of buildings. Considerable damage to shrubbery and trees, with some trees blown down. Considerable damage to mobile homes, poorly constructed signs, and piers. Coastal and low-lying escape routes flood 2-4 hours before arrival of the hurricane center. Small craft in unprotected anchorages break moorings.

18. Category 3 Hurricanes
Category 3: Winds mph. Storm surge generally 9-12 ft above normal. Some structural damage to small residences and utility buildings, with a minor amount of curtain wall (non-load-bearing exterior wall) failures. Damage to shrubbery and trees, with foliage blown off trees, and large trees blown down. Mobile homes and poorly constructed signs are destroyed. Low-lying escape routes are cut by rising water 3-5 hours before arrival of the center of the hurricane. Flooding near the coast destroys smaller structures, with larger structures damaged by battering from floating debris.

19. Category 4 Hurricanes
Category 4: Winds mph. Storm surge generally feet above normal. More extensive curtain wall failures, with some complete roof structure failures on small residences. Shrubs, trees, and all signs are blown down. Complete destruction of mobile homes. Extensive damage to doors and windows. Low-lying escape routes may be cut by rising water 3-5 hours before arrival of the center of the hurricane. Major damage to lower floors of structures near the shore. Terrain lower than 10 feet above sea level may be flooded.

20. Category 5 Hurricanes
Category 5: Winds greater than 155 mph. Storm surge generally greater than 18 feet above normal. Complete roof failure on many residences and industrial buildings. Some complete building failures, with small utility buildings blown over or away. All shrubs, trees, and signs blown down. Complete destruction of mobile homes. Severe and extensive window and door damage. Low-lying escape routes are cut by rising water 3-5 hours before arrival of the center of the hurricane. Major damage to lower floors of all structures located less than 15 feet above sea level and within 500 yards of the shoreline.

21. The Enhanced Fujita Tornado Scale (EF Scale)
EF-0. Light damage Wind 65 to 85 mph. Causes some damage to siding and shingles
EF-1. Moderate damage Wind 86 to 110 mph. Considerable roof damage. Winds can uproot trees and overturn single-wide mobile homes. Flagpoles bend.
EF-2. Considerable damage Wind 111 to 135 mph. Most single-wide mobile homes destroyed. Permanent homes can shift off foundation. Flagpoles collapse. Softwood trees debarked.
EF-3. Severe damage Wind 136 to 165 mph. Hardwood trees debarked. All but small portions of houses destroyed.
EF-4. Devastating damage Wind 166 to 200 mph. Complete destruction of well-built residences, large sections of school buildings.
EF-5. Incredible damage Wind above 200 mph. Significant structural deformation of mid- and high-rise buildings.

22. EF 0 Tornadoes
WS: 65–85 mph. Minor or no damage. Peels surface off some roofs; some damage to gutters or siding; branches broken off trees; shallow-rooted trees pushed over. Confirmed tornadoes with no reported damage (i.e., those that remain in open fields) are always rated EF0.

23. EF 1 Tornadoes
WS: 86–110 mph. Moderate damage. Roofs severely stripped; mobile homes overturned or badly damaged; loss of exterior doors; windows and other glass broken.

24. EF 2 Tornadoes
WS: 111–135 mph. Considerable damage. Roofs torn off well-constructed houses; foundations of frame homes shifted; mobile homes completely destroyed; large trees snapped or uprooted; light-object missiles generated; cars lifted off ground.

25. EF 3 Tornadoes
WS: 136–165 mph. Severe damage. Entire stories of well-constructed houses destroyed; severe damage to large buildings such as shopping malls; trains overturned; trees debarked; heavy cars lifted off the ground and thrown; structures with weak foundations are badly damaged.

26. EF 4 Tornadoes
WS: 166–200 mph. Extreme damage. Well-constructed and whole frame houses completely leveled; cars and other large objects thrown and small missiles generated.

27. EF 5 Tornadoes
WS: > 200 mph. Total destruction of buildings. Strong framed, well built houses leveled off foundations and swept away; steel-reinforced concrete structures are critically damaged; tall buildings collapse or have severe structural deformations; some cars, trucks and train trucks can be thrown approximately 1 mile.

28. The Doppler Radar “Hook”
tornado

29. The Joplin Tornado Doppler Radar Image