Download Atmospheric

Module 1: Themes in Physical
Geography
Topic 3: Weather
Unit A : Atmospheric heating, motion
(winds) and moisture
Unit B : Weather systems (air masses,
depressions, anticyclones) & their
interaction with humans
Unit C : Hurricanes and their impact on
people & property
A (i) Temperature
• Global energy
balance
• Vertical & horizontal
heat transfer
• The atmosphere is
fluid. Transfer of
energy is necessary
because of uneven
heating of globe.
• Heat is transferred
vertically by air
movement and
horizontally by wind
and ocean currents.
Meteorology is the study of atmospheric
phenomena (weather & climate).
Vertical structure of
atmosphere
The atmosphere is an
envelope of transparent,
odourless gases held to
the earth by gravitational
attraction. Most of our
weather happens in the
first 16km ( it extends to
1000km).
• Divided into 4 distinct
layers based on heat.
•
•
•
•
•
•
•
•
Thermosphere
Mesopause
Mesosphere
Stratopause
Stratosphere
Tropopause
Troposphere
Sea Level
Troposhere
• Environmental Lapse Rate 6.4 C
drop per 1000m up
• Earth’s surface heats air next to it
by conduction, convection &
radiation
• Pressure falls as effects of gravity
decrease
• Wind speeds increase with height
• Unstable layer as it contains most
of atmosphere’s water vapour,
cloud, dust & pollution
• Tropopause is an isothermal layer
– temperatures remain constant
Stratosphere
• Steady increase in temp. with
height caused by:
• Concentration of ozone O3
• Ozone absorbs incoming ultraviolet (UV) radiation.
• Winds increase with height
• Pressure decreases with
height
• Dry
• Protective shield against
meteorites
• Stratopause: isothermal layer
Mesosphere
• Temp. falls rapidly with height
• No water, cloud, dust or ozone
to absorb incoming solar
radiation
• Lowest temps. (-90 oC)
• Strongest winds (3000km/hr)
• Protective shield against
meteorites
• Mesopause – isothermal layer
Thermosphere
• Temp. rise rapidly with height
(up to 1500oC)
• Increased proportion of atomic
oxygen which , like ozone,
absorbs incoming UV radiation
Atmospheric Gases
Energy in the Atmosphere
SUN
1% absorbed in stratosphere
100%
Short-wave
solar radiation
(insolation)
Scattering of radiation
by dust particles
(volcanoes, deserts)
or by molecules of
gas. Happens in all
directions, some still
reaches earth’s
surface.
Diffuse radiation 21%
Absorption
(24%) of
incoming
radiation
by
wat.vap.,
CO2, ice &
dust.
Clouds
absorb 3%
Clouds reflect
(23%) radiation
back into space –
the thicker the
cloud the more
reflection
Albedo is the ratio
between incoming
radiation and the
amount reflected
expressed as a %
Direct
insolation
24%
45% reaches
earth’s surface
Earth surface causes reflection (4%)
– oceans reflect only 10%, grassland
25%, fresh snow 85% (albedo)
Page 206 – 208 Questions
1.
What methods are used by meteorologists to measure the change in temperature
with height in our atmosphere?
2.
By what 3 methods does the earth’s surface heat the air above it. Explain the
difference in these three methods – you will have to research this!
3.
Why do temperatures increase with height in the stratosphere?
4.
Temperatures fall rapidly in the mesosphere, why is this?
5.
Water vapour, carbon dioxide and ozone are found in very small amounts in our
atmosphere, but yet each is vitally important, explain why.
6.
What type of waves come directly from the sun?
7.
What 4 astronomical factors determine the amount of incoming radiation received
by the earth?
8.
Explain why cloud types affect temperatures at the earth’s surface.
Homework continued……..
9.
What 3 rolls can dust play in our atmosphere?
10.
a) What is desertification?
b) How is desertification influenced by a change in albedo?
11.
How are the terms scattering and diffuse radiation linked?
12.
What percentage of incoming radiation actually reaches the earth’s surface and
how does it get there?
13.
Explain what happens to incoming radiation when it reaches the earth’s surface.
14.
Why is the natural green house effect so important?
15.
What is long-wave radiation also known as and what is it?