Radiometric Corrections Atmospheric Corrections Atmospheric Effects on EMR.
Atmospheric
-
Upload
hyatt-chambers -
Category
Documents
-
view
24 -
download
1
description
Transcript of Atmospheric
![Page 1: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/1.jpg)
![Page 2: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/2.jpg)
Air Pressure Experiments
Lessons from Paper Cup experiment:
1. Air pressure is present everywhere
2. Air “tries to” move from an area of higher pressure to an area of low pressure
Lesson from Pop Bottle experiment:
3. Warm air occupies more space than an equal number of molecules of cold air
![Page 3: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/3.jpg)
Wind Power Generation in Southern Alberta
![Page 4: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/4.jpg)
“Don’t try this at home”
![Page 5: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/5.jpg)
The speed and direction of windis determined by three forces:
1. Pressure Gradient Force
2. Inertial Coriolis Force
3. Friction Force
![Page 6: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/6.jpg)
Pressure Gradient Force
H L102.2 99.8
101.4 100.6
600 km
Pressure Gradient Force = 2.4 kPa / 600 km= 0.4 kPa / 100 km
Definition:
The difference inatmosphericpressure per unitdistance
PGF acts at rightangles to isobarsof equal pressure
![Page 7: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/7.jpg)
Where is the PGF forecast to be strongest today ?
Regina orLethbridge?
Solution:Check the spacing of theisobars of equal surfacepressure
Source: http://weatheroffice.ec.gc.ca/data/model_forecast/592_100.gif
![Page 8: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/8.jpg)
The Inertial Coriolis Force
Objects moving in an “absolute” straight linebetween two points on the Earth’s surface aredeflected:
To the RIGHT in the N hemisphereTo the LEFT in the S hemisphere
Why ?
The Earth rotates more quickly at the equator.
![Page 9: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/9.jpg)
Visualizing the Coriolis Force
Source: NASA
![Page 10: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/10.jpg)
The Friction Force
Surface roughness decreases wind speed
Reduces impact of Inertial Coriolis Force
Winds cross isobars, spiralling out ofANTICYCLONES (H), and into CYCLONES (L)
H L
![Page 11: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/11.jpg)
Can you infer wind direction and relative speed from this map ?
weather.unisys.com
![Page 12: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/12.jpg)
![Page 13: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/13.jpg)
Sea level pressure:
AltitudeCorrection
Source: Ahrens (1994)
![Page 14: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/14.jpg)
Weather symbols andwind barbs
![Page 15: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/15.jpg)
Classic Low Pressure SystemIn Temperate Latitudes
SHARPCOLDFRONT
WARM,MOISTSOUTHERLYFLOW
NORTH-EASTWINDS
www.atmos.washington.edu
0600h GMTAPRIL 52003
![Page 16: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/16.jpg)
Cold Front
![Page 17: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/17.jpg)
Arctic high pressure drives cold arctic air behind low
![Page 18: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/18.jpg)
Warm Front
•Not as steep a division as in a cold front•It takes longer to scour out surface air (warm air rises)
![Page 19: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/19.jpg)
WARM, SOUTHWIND
COOLNW WIND
COLD FRONT
WARM FRONT
HURRICANE ISABEL
The weather pattern last September
![Page 20: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/20.jpg)
Main Low and High Pressure Zones
1. Equatorial Low Pressure Trough
2. Subtropical High Pressure Cells
3. Subpolar Low Pressure Cells
4. Weak Polar High Pressure Cells
![Page 21: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/21.jpg)
Atmospheric Circulation Overview
HADLEYCELL
FERRELCELL
POLARCELL
![Page 22: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/22.jpg)
Equatorial low pressure trough (warm, wet)
ITCZ shifts with season
High solar angle
HeatingConvergence
Consistent daylength
![Page 23: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/23.jpg)
Hadley Cells
1. Warm, moist air rises in equatorial lowCools, condenses, and causes heavy rain
2. Outward flow to subtropical high at high altitude
3. Air descends in subtropical highHeats, compresses and becomes very dry
4. The subtropical high provides the gradient for trade winds and westerlies
eg. Bermuda/Azores and Pacific/Hawaii highs
![Page 24: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/24.jpg)
Strahler and Strahler (2002)
![Page 25: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/25.jpg)
Ferrel Cells
Between subtropical highs and subpolar lows
Poleward transport of excess heat througheddies and migration of lows toward polar front
Strong low pressure develops in a belt aroundAntarctica, near the Aleutians and near Iceland
Lows strongest in winter (shift and diminish periodically, especially in the summer)
Why ? Water much warmer than land in winter leading to lower pressure over oceans
![Page 26: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/26.jpg)
H L
Air tends to be unstable in low pressure (tendency to rise)Air tends to be stable in high pressure (tendency to fall)
(more on stability in next class)
![Page 27: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/27.jpg)
WINTER SUMMER
Generalized Overview of Seasonal Surface Pressure
![Page 28: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/28.jpg)
Average GlobalSurface Pressurein January andJuly
Can you explainthe monsoon seasonof the Indian sub-continent with thischart ?
![Page 29: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/29.jpg)
Polar High Pressure Cells
Tendency for higher pressure near polesthan at the polar front
Anticyclonic flow develops
Weak and variable polar easterlies result(stronger in southern hemisphere)
In northern hemisphere winter, the polar front usually lies over Canada and Russia,(further south than in the summer)
![Page 30: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/30.jpg)
Geostrophic Winds 500 mbar height map
Lower heightswhere air is cold
Airflow parallel to isobars inupper troposphere
Why ?
Combination of PGF and Coriolis force
Source: http://weatheroffice.ec.gc.ca/data/model_forecast/134_100.gif
![Page 31: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/31.jpg)
Source: Ahrens (1994)
Effect of Air temperature on 500 mb heights
![Page 32: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/32.jpg)
Upper Atmospheric Circulation
Jet StreamsA band of wind in the upper troposphere
150 – 500 km wide0.9-2.2 km thickSpeeds may exceed 300 km/h
Polar Jet Stream: Between Polar and Ferrel cells
Subtropical Jet Stream: Between Hadley and Ferrel Cells
![Page 33: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/33.jpg)
Source: http://apollo.lsc.vsc.edu
![Page 34: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/34.jpg)
Source: http://apollo.lsc.vsc.edu
![Page 35: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/35.jpg)
Tropopauseheight
18 000 m
12 000 m
6 000 m
Discontinuity orstep in tropopause height
“Rivers” of strong wind where cold and warm meet
Jet Stream Cross Section
See: www.avsim.com/avwx/avsim_wxus_jetstream.html
![Page 36: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/36.jpg)
Polar Jet Stream
Subtropical Jet Stream
Meanders from 30-70° N or S
Moves more poleward in summer
Influences (and is influenced by) storm paths
Meanders from 20-50° N or S
May occur simultaneously with Polar Jet in NA
![Page 37: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/37.jpg)
Rossby Waves
The polar jet stream follows the Rossby Waves
Rossby Waves are undulations in the upper-airwesterlies extending from the middle to upper troposphere
Form along the polar front
Mechanism of poleward heat transport
![Page 38: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/38.jpg)
(Strahler and Strahler, 2002)
![Page 39: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/39.jpg)
Daytime
![Page 40: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/40.jpg)
Night
Source: Ahrens, 2001
![Page 41: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/41.jpg)
Mountain Valley Breezes
Source: http://apollo.lsc.vsc.edu
Daytime
The sun heats the hillslope, causing air to move up theslope
Night
Night radiation coolsthe slopes
Cooler, denser air moves downslope
![Page 42: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/42.jpg)
Katabatic Winds
•Air cools on a plateau or sloping terrain, becomes more dense and descends
•Winds get faster and faster downslope
•Relatively warm water at base can further increase winds, which can be very strong as a result
•Can occur on large scale (eg. Greenland, Antarctica)
•Also referred to as gravity drainage winds
![Page 43: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/43.jpg)
VANCOUVER LETHBRIDGE8°C 12°C
X X
CoolingAt MALR6°C/km
WarmingAt DALR10 °C/km
CoolingAt DALR10 °C/km
CoolingAt MALR6°C/km
WarmingAt DALR10 °C/km
More sensible heat
Chinook Winds
![Page 44: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/44.jpg)
•Water piles up around equator due to trade winds
•Along western edge of oceans, water spills N and S along shorelines of continents (also downwelling)
•Upwelling occurs near east edge of oceans (west coasts)
![Page 45: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/45.jpg)
Upwelling of cool waters
![Page 46: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/46.jpg)
Result: The water column becomes unstable and mixes vertically in the north. This newly formed water is carried southward at great depths - North Atlantic Deep Water (NADW)
The Thermohaline Circulation
(1) Intensive cooling at the ocean surface in North Atlantic(2) Northward transport of salty surface water from lower latitudes (both increase the density).
![Page 47: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/47.jpg)
Interannual climatic variability atthe global scale
Caused by changing atmospheric andoceanic circulation in the tropicalPacific Ocean
![Page 48: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/48.jpg)
Top La Nina December 1998; Middle Normal December 1993; Bottom El Nino Dec 1997
![Page 49: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/49.jpg)
See http://www.cdc.noaa.gov/map/clim/sst_olr/sst_anim.shtml
![Page 50: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/50.jpg)
![Page 51: Atmospheric](https://reader036.fdocuments.in/reader036/viewer/2022062516/56812bcb550346895d9023d1/html5/thumbnails/51.jpg)