Download STRUCTURE OF THE ATMOSPHERE

WEATHER AND CLIMATE
• WEATHER = the state of the atmosphere
at a given time and place. Temperature,
sunshine or cloud and the level of rainfall
and humidity.
• CLIMATE = the average weather
conditions of a place or an area over a
period of 30 years or more.introclimate.ppt
http://www.educapoles.org/multimedia/animation_detail/what_is_the_atmosphere/
STRUCTURE OF THE ATMOSPHERE
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Keywords Science weather
Page 17 This is an animation of the structure of the atmosphere.
Website 2 What is the atmosphere?
The composition of the atmosphere
The atmosphere is a mixture of transparent gases held to
the Earth by gravitational force.
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NITROGEN = 78.09%
OXYGEN =20.95%
WATER VAPOUR
CARBON DIOXIDE
OZONE
ARGON
The top of the atmosphere is at 1000km from the
Earths surface, but due to gravity and
compression 50% of it lies within 5.6km of the
surface and 99% within 40km.
The atmosphere:
It is a mixture of gases, with
some liquids and solids, held
close to the Earth by gravity.
The structure of the atmosphere
The atmosphere
• Extends 1,000km from Earth,
• Most, in terms of mass, is concentrated in
the lower 16km,
• 50% is found below 6km,
• Troposphere
• Stratosphere
• Mesosphere
• Thermosphere
The atmospheric heat budget
• Energy from the sun,
• This is incoming solar radiation = INSOLATION,
• Outgoing energy from the Earth = RADIATION,
• These must balance and this is the heat budget!
• Some parts of the Earth receive more insolation
than others and the Earth tries to move this heat
around via winds and ocean currents.
The amount of energy received
from the sun is determined by:
• 1. The solar constant – varies slighty and affects
longer-term climate,
• 2. The distance from the sun – the eccentric
orbit of the earth around the sun can cause up to
6% variation in the solar constant,
• 3. The altitude of the sun in the sky- differential
heating (diagram),
• 4. The length of day and night – the 23.5 tilt of
the Earth means that regions near the poles
(north of 66.5N or south of 66.5S) receive no
solar insolation at certain times of the year.
The heat budget
The heat budget:
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Albedo,
Short-wave radiation,
Long-wave radiation,
Latent heat.
(Use dictated notes here).
Spatial variations in energy and
heat.
• DIFFERENTIAL HEATING causes an imbalance
with low latitudes gaining a surplus of energy
from the sun, whilst high latitudes have a deficit.
• This imbalance is rectified by the following heat
transfers:
• 1. Horizontal heat transfers- winds and ocean
currents,
• 2. Vertical heat transfers- radiation, conduction,
convection and latent heat.
Factors affecting insolation and the
heating of the atmosphere.
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Long-term:
Altitude of land,
Altitude of the sun,
Proportion of land and sea,
Prevailing winds,
Ocean currents,
Ocean conveyor belt.
Dictate additional notes and copy of ocean
currents on world map.
Ocean currents related to winds.
Short-term:
• Seasonal changes- In the summer and winter
when the sun is directly overhead at the tropics,
maximum insolation is experienced in the
northern and southern hemisphere respectively,
• Diurnal range- At the poles there is no insolation
during winter months when the regions tilt away
from the sun and 24 hours of daylight in the
summer when tilted towards the sun.
Local factors:
• Aspect – north or south facing slopes,
• Cloud cover- clouds reflect, absorb and scatter
incoming radiation, but also keep heat in the
lower atmosphere. Clear skies allow more solar
insolation in the day, but at night more radiation
reduces temperatures. When it is cloudy
temperatures do not fall or rise as much.
• Urbanisation- urban surfaces absorb more heat,
creating urban heat islands.