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Heat Transfer: Warming Air through Layered Conduction
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- Transfer of Heat: The air in contact with the land gets heated slowly and the upper layers in contact with the lower layers also get heated due to the transfer of heat from the warmer to the cooler body.
- This process is called conduction.
- Layered Heat Transfer: This process continues until both bodies reach the same temperature or contact is broken.
- The conduction primarily heats the atmosphere’s lower layers.
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Rising Heat: Convection in Earth’s Atmosphere
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- Definition: Air in contact with the earth rises vertically when heated, forming currents that transmit atmospheric heat.
- This vertical heating process is termed as convection.
- Location: The convection-based energy transfer is limited to the troposphere.
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Advection’s Impact: Heat Shifts in Air Movement
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- Definition: The transfer of heat through horizontal movement of air is called advection.
- Importance: Horizontal air movement is more important than vertical movement.
- Importance: In middle latitudes, daily weather variations (diurnal) are mainly due to advection. In tropical regions, especially in northern India during summer, local winds like ‘loo’ result from the advection process.
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Earth’s Heat Exchange: Insolation to Radiation
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- Earth’s Absorption: The earth absorbs insolation in short waveforms, warming its surface.
- Radiation: Once heated, the earth becomes a radiator, emitting energy back to the atmosphere in long waveforms.
- This emitted energy is termed “terrestrial radiation.”
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Atmosphere’s Role: Absorbing, Radiating Earth’s Heat
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- Atmospheric Absorption: The atmosphere absorbs long-wave radiation, especially from gases like carbon dioxide and other greenhouse gases.
- Atmospheric Radiation: This means the atmosphere gets its warmth indirectly from the earth’s radiation, rather than directly from the sun.
- After absorbing this energy, the atmosphere then radiates heat back into space.
- Energy Balance: This ensures a balance, where the heat the earth receives from the sun is eventually returned to space, maintaining a constant temperature both on the earth’s surface and in the atmosphere.
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