5.2 Energy Transfer in the Atmosphere

Energy transfer in the atmosphere is a crucial process that shapes Earth's climate. Radiation, conduction, and convection move heat around, while latent heat from water's phase changes plays a big role too. These mechanisms work together to distribute energy globally.

The greenhouse effect, driven by gases like CO2 and water vapor, traps heat and keeps Earth warm. Human activities are boosting greenhouse gas levels, leading to global warming. Understanding these processes is key to grasping climate change and its impacts.

Energy transfer mechanisms in the atmosphere

Radiation, conduction, and convection

Top images from around the web for Radiation, conduction, and convection

• 

  Conduction | Physics View original

  Is this image relevant?

• 

  Convection · Physics View original

  Is this image relevant?

• 

  1.6 Mechanisms of Heat Transfer – University Physics Volume 2 View original

  Is this image relevant?

• 

  Conduction | Physics View original

  Is this image relevant?

• 

  Convection · Physics View original

  Is this image relevant?

1 of 3

Top images from around the web for Radiation, conduction, and convection

• 

  Conduction | Physics View original

  Is this image relevant?

• 

  Convection · Physics View original

  Is this image relevant?

• 

  1.6 Mechanisms of Heat Transfer – University Physics Volume 2 View original

  Is this image relevant?

• 

  Conduction | Physics View original

  Is this image relevant?

• 

  Convection · Physics View original

  Is this image relevant?

1 of 3

• Radiation transfers energy through electromagnetic waves (visible light, infrared, ultraviolet radiation from the Sun)
• Conduction transfers energy through direct contact between molecules
  • Heating of air in contact with the Earth's surface
• Convection transfers energy through the movement of fluids or gases
  • Rising of warm air and sinking of cool air in the atmosphere
  • Plays a crucial role in atmospheric circulation patterns (Hadley cells, jet streams)

Latent heat and energy balance

• Latent heat is the energy absorbed or released during phase changes of water (evaporation, condensation)
  • Plays a significant role in atmospheric energy transfer
  • Evaporation of water from Earth's surface absorbs energy, while condensation releases energy in the atmosphere
• Earth's surface and atmosphere absorb, reflect, and emit radiation at different wavelengths
  • Absorption of solar radiation by Earth's surface and atmosphere
  • Reflection of solar radiation by clouds, aerosols, and Earth's surface
  • Emission of infrared radiation by Earth's surface and atmosphere

The greenhouse effect and Earth's temperature

Greenhouse gases and their role

• Greenhouse effect is a natural process in which atmospheric gases absorb and re-emit infrared radiation from Earth's surface
  • Gases include carbon dioxide, water vapor, methane, nitrous oxide, and ozone
• Greenhouse gases allow shorter-wavelength solar radiation to pass through the atmosphere and reach Earth's surface
  • Gases trap longer-wavelength infrared radiation emitted by Earth
• Trapped infrared radiation warms Earth's surface and lower atmosphere
  • Maintains a temperature range suitable for life (average surface temperature of 15°C or 59°F)

Anthropogenic influence and climate change

• Anthropogenic activities have increased the concentration of greenhouse gases in the atmosphere
  • Burning fossil fuels (coal, oil, natural gas) releases carbon dioxide
  • Deforestation reduces carbon dioxide absorption by plants and releases stored carbon
• Enhanced greenhouse effect leads to global warming and climate change
  • Observed increase in global average surface temperatures since the late 19th century
  • Projected further warming and associated impacts (sea level rise, changes in precipitation patterns, more frequent and intense extreme weather events)
• Greenhouse effect is a delicate balance, and changes in greenhouse gas concentrations can significantly impact Earth's climate system
  • Positive feedback loops can amplify warming (melting of Arctic sea ice reduces albedo and increases absorption of solar radiation)
  • Negative feedback loops can mitigate warming (increased evaporation leads to more cloud formation, reflecting more solar radiation)

Factors influencing Earth's energy budget

Solar radiation and albedo

• Solar radiation is the primary source of energy for Earth's climate system
  • Amount of incoming solar radiation varies based on latitude, season, and time of day
  • Solar radiation peaks at the equator and during summer in each hemisphere
• Albedo is the measure of a surface's reflectivity
  • High-albedo surfaces (snow, ice) reflect more solar radiation
  • Low-albedo surfaces (oceans, forests) absorb more solar radiation
  • Changes in Earth's surface albedo can affect regional and global climate (melting of Arctic sea ice, expansion of deserts)

Atmospheric absorption and clouds

• Atmospheric absorption occurs when gases absorb incoming solar radiation and outgoing infrared radiation
  • Water vapor and carbon dioxide are the most significant absorbers
  • Absorption by gases influences Earth's energy balance and greenhouse effect
• Clouds play a complex role in Earth's energy budget
  • Clouds can reflect incoming solar radiation, producing a cooling effect
  • Clouds can trap outgoing infrared radiation, producing a warming effect
  • The net effect of clouds depends on their type, altitude, and optical properties (low, thick clouds tend to cool; high, thin clouds tend to warm)
• Changes in land use can alter Earth's surface albedo and energy balance
  • Deforestation reduces absorption of solar radiation and carbon dioxide
  • Urbanization increases absorption of solar radiation and heat storage in buildings and infrastructure

Atmospheric stability and air movement

Stability and vertical motion

• Atmospheric stability refers to the atmosphere's resistance to vertical motion
  • Determined by the vertical temperature gradient (lapse rate) and presence of moisture
• In a stable atmosphere, the environmental lapse rate is less than the adiabatic lapse rate
  • Suppresses vertical air movement and leads to limited convection and mixing
  • Occurs when air temperature decreases slowly with height or increases with height (temperature inversion)
• In an unstable atmosphere, the environmental lapse rate is greater than the adiabatic lapse rate
  • Promotes vertical air movement, convection, and formation of clouds and precipitation
  • Occurs when air temperature decreases rapidly with height
• Conditionally unstable atmospheres are stable when unsaturated but become unstable when saturated
  • Leads to the development of convective clouds and storms under certain conditions (daytime heating, uplift of moist air)

Implications for air quality and weather

• Atmospheric stability influences the dispersion of pollutants
  • Stable conditions lead to the accumulation of pollutants near the surface (smog, haze)
  • Unstable conditions promote the mixing and dispersion of pollutants
• Temperature inversions create highly stable conditions that can trap pollutants and moisture near the surface
  • Leads to poor air quality and fog formation, especially in urban and industrial areas
  • Common in valleys and basins, where cold air can pool near the surface
• Atmospheric stability affects the development and intensity of weather systems
  • Unstable conditions favor the formation of convective storms (thunderstorms, tornadoes)
  • Stable conditions favor the formation of stratiform clouds and steady precipitation