X. Human Impact on Atmospheric Energy:
Human can alter the energy balance and thus the temperature of the atmosphere over different space and time-scales by deliberate or unconscious action with beneficial or harmful results.
The energy balance is altered by:
- changing the nature and composition of the atmosphere; and
- altering the character of the earth's surface.
The urban heat island effect can be explained in part by atmospheric change through heat release and pollution emission from city areas.
The heat storage capacity and dry surface character of city structures also contribute to the urban heat island effect.
Increased anthropogenic (man-made) accumulations of carbon dioxide have been implicated as a potential cause of global warming. Such warming may enhance aridity in the mid-latitudes and cause rising sea levels due to glacier melt.
Particulate emission, whether by natural or anthropogenic means, may contribute to a global cooling effect.
Human modification of the earth's surface albedo, in particular by desertification, may also be responsible for planetary cooling.
Table below shows the typical climatic changes caused by urbanization.
Typical climatic changes caused by urbanization
Type of change Comparison with rural env.
Annual mean 0.5-1.0oC higher
Winter mean 1.0-3.0oC higher
Annual mean 6 % lower
Winter 2 % lower
Summer 8 % lower
Dust particles 10 times more
Cloud cover 5 - 10% more
Fog, winter 100 % more frequent
Fog, summer 30 % more frequent
Total on horizontal surface 15-20 % less
Ultraviolet, winter 30 % less
Ultraviolet, summer 5 % less
Annual mean 20 -30 % lower
Extreme gusts 10 -20 % lower
Calms 5 - 20 % more
Amounts 5 - 10 % more
Days with over 0.5 cm 10 % more
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