The Layered Atmosphere

1
The Layered Atmosphere

• The Earth's atmosphere contains several different
  layers that can be defined according to air
  temperature

2
Troposphere

• According to temperature, the atmosphere contains
  four different layers (Figure 7b-1). The first
  layer is called the troposphere.
• The depth of this layer varies from about 8 to 16
  kilometers.
• Greatest depths occur at the tropics where warm
  temperatures causes vertical expansion of the
  lower atmosphere. From the tropics to the Earth's
  polar regions the troposphere becomes gradually
  thinner. The depth of this layer at the poles is
  roughly half as thick when compared to the
  tropics.
• Average depth of the troposphere is approximately
  11 kilometers as displayed in Figure 7b-1

3
Stratosphere

• Above the tropopause is the stratosphere.
• This layer extends from an average altitude of
  11 to 50 kilometers above the Earth's surface.
• This stratosphere contains about 19.9 of the
  total mass found in the atmosphere. Very little
  weather occurs in the stratosphere. Occasionally,
  the top portions of thunderstorms breach this
  layer.
• The lower portion of the stratosphere is also
  infuenced by the polar jet stream and subtropical
  jet stream. In the first 9 kilometers of the
  stratosphere, temperature remains constant with
  height.

4
Stratosphere

• A zone with constant temperature in the
  atmosphere is called an isothermal layer.
• From an altitude of 20 to 50 kilometers,
  temperature increases with an increase in
  altitude. The higher temperatures found in this
  region of the stratosphere occurs because of a
  localized concentration of ozone gas molecules.
• These molecules absorb ultraviolet sunlight
  creating heat energy that warms the stratosphere.
  Ozone is primarily found in the atmosphere at
  varying concentrations between the altitudes of
  10 to 50 kilometers.
• This layer of ozone is also called the ozone
  layer . The ozone layer is important to organisms
  at the Earth's surface as it protects them from
  the harmful effects of the sun's ultraviolet
  radiation. Without the ozone layer life could not
  exist on the Earth's surface.

5
Stratopause Mesosphere

• Separating the mesosphere from the stratosphere
  is transition zone called the stratopause.
• In the mesosphere, the atmosphere reaches its
  coldest temperatures (about -90 Celsius) at a
  height of approximately 80 kilometers.
• At the top of the mesosphere is another
  transition zone known as the mesopause.

6
Thermosphere

• The last atmospheric layer, as defined by
  vertical temperature change, has an altitude
  greater than 80 kilometers, and is called the
  thermosphere.
• The thermosphere is the hottest layer in the
  atmosphere.
• Heat is generated from the absorption of solar
  radiation by oxygen molecules.
• Temperatures in this layer can reach 1300 to
  1800 Celsius.

7
SUN 100
-31 units (Albedo) Reflected back to space
Energy absorbed in Stratosphere 3 units Ozone
-7
-21
-3
Scattering
Energy absorbed in Troposphere 18 units ( gases
,dust)
Clouds Absorbed 3 units
25 direct
10
10
Total energy absorbed at surface 45 units
8
Energy radiated to space Total 69 units
Energy from Long wave radiation 46 units
Non radiative exchanges 23 units

-3 units of UV from ozone layer
-21 units from the atmosphere heat input
-14 units from the greenhouse effect
-8 units of direct heat loss from the earths
surface
9
Energy gained and lost by the greenhouse effect
Total 14 units
Downward radiation 96 units
Long wave radiation -110 units
10
Non Radiative exchanges
Convective (turbulent) transfer - 4 units
Latent heat transfer (evaporation) -19 units
11
Energy Budget variation with Latitude
12
90o N
40o N
Equator 0o
GAIN
40o S
90o S
13
Simple Model of Global Circulation
14
Three Cell Model of Global Circulation
15
Polar
High
Northern Hemisphere
Ferrel
Low
High
Hadley
Diagram showing the Tricellular Model
Equator
Low
Southern Hemisphere
16
Depressions a mid latitude vortex
17
Depressions a mid latitude vortex
18
Depressions a mid latitude vortex
19
Origin
20
Maturity
21
Occlusion
22
The passage of a mature depression across the
United Kingdom
23
Anticyclones
24
Air-mass types

• There are four main types of air mass
• Tropical continental (Tc)
• Tropical maritime (Tm)
• Polar continental (Pc)
• Polar maritime (Pm)
• And two further sub-divisions
• Arctic maritime (Am)
• Returning polar maritime (rPm)

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Energy lost to Space
High Sun 13
Low Sun 5
Greenhouse gas
Cloud Type
Long Wave Radiation Net Radiation Balance
Evaporation Latent energy
Reflection from ground. Albedo
Surface Absorption of energy
27
Ground Frost
28
Walled Garden
29
Smudge Pots
30

• Tablas Creek uses frost-prevention fans in early
  spring to protect against radiation frosts, where
  cold air settles near the surface

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Problems of Ice
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