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The Layered Atmosphere

The Layered Atmosphere. The Earth's atmosphere contains several different layers that can be defined according to air temperature. Troposphere. According to temperature, the atmosphere contains four different layers ( Figure 7b-1 ). The first layer is called the troposphere .

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The Layered Atmosphere

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  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 +10 +10 +25 direct 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 earth’s 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 GAIN Equator 0o 40o S 90o S

  13. Simple Model of Global Circulation

  14. Three Cell Model of Global Circulation

  15. Polar High Northern Hemisphere Low Ferrel 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)

  25. 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

  26. Ground Frost

  27. Walled Garden

  28. Smudge Pots

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

  30. Problems of Ice

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