1 atmosphere - temp profile wind
DESCRIPTION
1 Atmosphere - Temp Profile WindTRANSCRIPT
The atmosphere
• The most significant area of the atmosphere from a meteorological aspect is the Troposphere. It contains 75% of the atmosphere and 90% of the water vapour and is where most of the meteorological activity occurs.
• Various temperature gradients exist in the atmosphere but the most significant is the change at the Tropopause. This area tends to act as a barrier at different heights to the air in the troposphere, which moves in specific ways.
Composition of the atmosphereGases (invisible) Percentage by volume•Nitrogen 78.09•Oxygen 20.95•Carbon dioxide 00.03•Other constituents – in variable quantities•Water vapour (invisible) – Up to 4% by volume
•Dust particles including clay minerals e.g. kaolinite•Salt particles – Sodium chloride
‘condensation nuclei’
Atmospheric Pressure
• The surface air pressure at any point will be equal to the density of the air in the column, times the height of the column and gravity.
• The density of the air is controlled by the amount air moving in or out, at the top or bottom of the column.
Atmospheric Pressure
Force exerted by a column of air on unit area of the earth’s surface.
Units:– hectopascals – hPa, – millibars - mb (1hPa 1 mb)
2
P = ghP – Pressure - mean density of the airg – gravityh – height of the air column
Atmospheric Pressure
• If the convergence at the troposphere exceeds the divergence at the surface then a high pressure develops at the surface.
• If convergence at the surface exceeds divergence at the troposphere a low pressure develops at the surface.
• The net result from two adjacent areas is a flow of air from the high to the low pressure
Complete diagram
Page 6
Standard Atmosphere - Temperature Profile
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Temperature (deg C)
Hei
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TroposphereTropopause
Stratosphere
Standard Atmosphere - Temperature Profile
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Troposphere
Av ht?__________
TroposphereTropopause
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Troposphere
Av ht?___12km___
Poles?__________
Equator?________
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Troposphere
Av ht?___12km___
Poles?___8-9km__
Equator?_16 km__
TroposphereTropopause
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Av ht?___12km___
Note – ht of Tropopause is constantly changing
Varies with latitude & season
TroposphereTropopause
Standard Atmosphere - Temperature Profile
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TroposphereAv T° at Surface?
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Standard Atmosphere - Temperature Profile
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TroposphereAv T° at Surface? 15°C
Av T° Tropopause
Poles?
Equator?
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Standard Atmosphere - Temperature Profile
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TroposphereAv T° at Surface? 15°C
Av T° Tropopause
Poles? -60°C
Equator? -80°C
TroposphereTropopause
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Stratosphere
Contains 75% of the total atmospheric mass i.e. gases
Standard Atmosphere - Temperature Profile
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Troposphere,
Why does T° decrease with height?
TroposphereTropopause
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Troposphere,
Why does T° decrease with height?
“Warmed from the bottom up”.
Process?
TroposphereTropopause
• How is the troposphere heated?
Sensible heat (23%)
Latent Heat (77%)
Standard Atmosphere - Temperature Profile
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Why does T° increase with height?
TroposphereTropopause
Stratosphere
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Why does T° increase with height?
OZONE
Absorbs & filters out UV radiation – leads to warming of strat.
TroposphereTropopause
StratosphereContains OZONE (max)
Standard Atmosphere - Temperature Profile
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Thermosphere – important 4 life!
Atomic oxygen (O) – absorbs UV radiation – would cause skin cancer
TroposphereTropopause
Stratosphere
Mesosphere
Thermosphere
Troposphere- Page 7
1. Uniform decrease in temperature with height (10°C - 6.5°C km-1)
2. Wind speed increases with height (no friction).
3. Contains virtually all water vapour (and clouds).
4. Contains “the weather”.5. Contains all major
atmospheric pollution.