Explain the forces that generate winds Explain why there is well-developed westerly flow in the...
Transcript of Explain the forces that generate winds Explain why there is well-developed westerly flow in the...
![Page 1: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/1.jpg)
Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure systems Compare and contrast surface and geostrophic winds Describe/read maps of constant pressure surfacesIdentify and discuss wind types and the forces that generate them Recognize surface and upper-level atmospheric maps and identify general patterns of windflow Explain monsoonal flow and land-sea breezes
Air pressure and atmospheric motion
![Page 2: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/2.jpg)
Air pressure and atmospheric motion
Q: What makes the wind blow?
A: Air pressure differences.
![Page 3: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/3.jpg)
Air pressure
• Force exerted by molecules in atm due to gravity and temperature
![Page 4: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/4.jpg)
Air pressure
![Page 5: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/5.jpg)
![Page 6: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/6.jpg)
Surface air pressure variability
• Average sea level pressure 1013 mb
![Page 7: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/7.jpg)
Mercury barometer1013 mb = 29.91 inches
Aneroid barometer
![Page 8: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/8.jpg)
![Page 9: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/9.jpg)
Pressure systems
• Two types: high and low
• Low: associated with clouds and instability.
• High: associated with clear conditions and stability
![Page 10: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/10.jpg)
Low pressure systems
• Cyclone• Converging rising air at
surface• Diverging air aloft• Winds rotate
counterclockwise in NH• Areas of “light” atmosphere;
air is forced into these locations
• Unstable surface conditions
![Page 11: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/11.jpg)
High pressure system
• Anticyclone• Converging air aloft• Diverging sinking air at
surface• Winds rotate clockwise in
NH• Areas of “heavy”
atmosphere; air is forced out of these locations
• Stable surface conditions
![Page 12: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/12.jpg)
![Page 13: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/13.jpg)
Is the location for these pressure systems the northern or the southern hemisphere?
![Page 14: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/14.jpg)
High and low pressure systems
• Occur on a variety of spatial and temporal scales– Some pressure systems may be stationary for a
long period of time, others may migrate rapidly around the planet
– Some pressure systems are closed, others are more belt-like and open
![Page 15: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/15.jpg)
Low pressure systems
• Types of low pressure systems: tornados, thunderstorms, hurricanes….
![Page 16: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/16.jpg)
Low pressure systems
….., midlatitude cyclones, the ITCZ, thermal lows
![Page 17: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/17.jpg)
Dust devil versus ITCZ
![Page 18: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/18.jpg)
Another secret of weather forecasting
• The atmosphere is a heterogeneous collection of pressure systems in three dimensions.
• Weather forecasting involves looking at surface conditions as well as upper level conditions (aloft, in the upper troposphere)
• http://weather.unisys.com/
![Page 19: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/19.jpg)
• A midlatitude cyclone is a low pressure at the surface coupled to a low pressure aloft in the upper troposphere
• A hurricane is a high pressure aloft and a low pressure at the surface
“Deep” tropospheric phenomena
![Page 20: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/20.jpg)
Midlatitude cyclones
• Strong, “deep” interaction between surface and upper levels
• May travel large distances around the globe
Midlatitude cyclone
![Page 21: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/21.jpg)
“Shallow” tropospheric phenomena
• Thermal low (warm)• Thermal high (cold)
– Weak interaction between surface and upper levels
– May occur on a daily basis or persist over many months
L H
![Page 22: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/22.jpg)
Pressure differences initiate…..
![Page 23: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/23.jpg)
…….winds• Named according to the
direction they blow from• Winds can blow at different
directions at different altitudes in the atm
• Forces that act on winds:– PGF– CF– Surface friction
![Page 24: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/24.jpg)
![Page 25: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/25.jpg)
![Page 26: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/26.jpg)
1. PGF: Pressure gradient force – winds blow from high to low
Where are winds the fastest?
![Page 27: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/27.jpg)
2. Coriolis Force (CF)• Apparent deflection of the winds due to
rotation of the Earth – NH winds deflected right– SH winds deflected left
![Page 28: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/28.jpg)
Coriolis Force (CF)
• CF is not a true force; it is an apparent force arising from the effect of the Earth’s rotation
• Deflection is strongest at poles and zero at the Equator
• CF acts perpendicular to the direction of motion
• CF deflects to the right in the Northern Hemisphere
![Page 29: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/29.jpg)
Bart versus Australia
![Page 30: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/30.jpg)
Misconceptions about the Coriolis Force
• The CF does not determine the rotation in a drain.
![Page 31: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/31.jpg)
3. Surface friction (SF)
• Topography (mnts, elevated plateaus) deflect winds
![Page 32: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/32.jpg)
Two major types of winds
1. Geostrophic (upper troposphere winds)– Influenced by PGF and CF only– Wind flow is parallel to
isobars/geopotential heights– Geostrophic flow is westerly
(west to east) in NH– Shown on geopotential height
maps
![Page 33: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/33.jpg)
Geostrophic winds on geopotential height map
![Page 34: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/34.jpg)
Two major types of winds
2. Surface winds– Influenced by
PGF, CF, and SF
– Winds cross isobars
![Page 35: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/35.jpg)
Types of surface winds• Monsoonal flow
– Creates extreme wet and dry seasons
![Page 36: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/36.jpg)
Location ofthermal highsand lows associatedwith monsoonalflow
Monsoon in India
![Page 37: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/37.jpg)
![Page 38: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/38.jpg)
![Page 39: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/39.jpg)
Weak monsoonal flow in southwestern US
Winter Summer
![Page 40: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/40.jpg)
Types of surface winds
• Land-sea breeze circulation• Many other different types of
surface winds based on local physiography and arrangement of pressure cells. Many have unique names.
![Page 41: Explain the forces that generate winds Explain why there is well-developed westerly flow in the upper troposphere Differentiate between high and low pressure.](https://reader036.fdocuments.net/reader036/viewer/2022062518/56649ccb5503460f94994dfb/html5/thumbnails/41.jpg)
Sea breeze blowingfrom ocean to land