Module 2_LectureSlidesNotesAirTemperature

Module 2: Air Temperature Topics

• Solar Energy and its Role

• Electromagnetic Radiation (EMR) Characteristics

• Heat Transfer Processes

• Earth's Insolation

• Global Energy Budget

Solar Energy

• Driving force of most motion in the atmosphere

• Directly/indirectly controls weather and climate

• Affects all systems influenced by weather and climate

Nuclear Fusion

• Solar energy is produced by nuclear fusion in stars

• Energy equation: E=mc² (energy = mass x speed of light squared)

• A fundamental source for weather phenomena

Characteristics of EMR

• EMR possesses both electric and magnetic properties

• Travels at approximately 186,000 miles per second in space

• Speed is reduced when transmitted through planetary atmospheres

Wave Properties of EMR

• EMR transfers energy in waveforms; described by wavelength and frequency

• Wavelength range: from less than ~10 billionths of a yard to more than 100,000 yards

Temperature and EMR

• Higher temperatures correspond to shorter wavelengths of emitted radiation

• Hot objects primarily emit short wavelengths; cooler objects emit long wavelengths

• The electromagnetic spectrum divided into sections based on wavelength and energy

Radiation Types

• Shortwave (solar radiation) vs Longwave (thermal radiation)

• Scattering of sunlight influences atmospheric properties

Heat Transfer Processes

• Methods of heat transfer in the Earth's atmosphere include:

  • Radiation: Transfer without physical contact

  • Conduction: Heat transfer via physical contact (e.g., touching a hot stove)

  • Convection: Vertical motion due to density differences in air

  • Advection: Horizontal heat movement, e.g., warm fronts

  • Latent Heat of Condensation: Heat involved in phase changes of water

Conduction and Convection

• Conduction: Heat moves from hotter to cooler objects

  • Example: Heat felt when touching a hot stove

• Convection: Air moves vertically due to temperature differences, creating convection currents

  • Moist convection leads to cloud formation; dry convection describes warmth rising from surfaces

Earth's Energy Budget

• Energy budget balances incoming solar energy versus energy lost to space

• Factors influencing energy balance:

  • Earth's distance from the Sun

  • Variations in solar output

  • Earth-Sun relationship including seasonal changes

Insolation Fate

• Solar energy influences:

  • Absorption by atmosphere (16%)

  • Reflection by clouds and surface

  • Energy transformed into latent heat by vapor

  • Heat redistributed by ocean currents and atmospheric processes

Albedo

• Albedo measures light reflection percentage from surfaces

• High albedo objects (e.g., snow) absorb less energy; dark surfaces (e.g., asphalt) absorb more

• Different Earth surfaces have varying albedo values affecting temperature and heat absorption

Factors Affecting Insolation**

1. Albedo

2. Sunlight intensity and duration

3. Latitude

4. Cloud cover

5. Slope aspect

6. Proximity to water

7. Altitude

Temperature Variation by Latitude

• Temperature variations at different latitudes due to:

  • Distance from the equator

  • Ocean currents

  • Land-sea contrasts

Cloud Cover Effects

• Cloudy days lead to lower surface temperatures

• Cloudy nights help trap heat, leading to warmer surface temperatures

Slope Aspect Influence

• North vs. south-facing slopes in the Northern Hemisphere:

  • North-facing slopes are cooler and moister

  • South-facing slopes receive more solar energy and are warmer

Maritime vs. Continental Temperature Effects

• Maritime locations generally have moderated temperatures due to ocean currents

• Continental climates experience more extreme temperatures due to less influence from water bodies

Altitude Effects on Temperature

• Normal lapse rate: 3.5°F per 1000 ft (6.5°C per 1000 m)

• Temperature decreases with increasing altitude

Temperature Data and Indices**

• Daily mean temperature calculated from daily maxima and minima

• Heat index combines temperature and humidity to assess comfort levels

• Wind chill describes the perceived decrease in temperature due to wind speed

Conclusion: Key Impacts on Temperature

• Seasons result from axial tilt and orbit around the Sun

• Latitude influences sunlight intensity and duration

• Variations in temperature are affected by local geographic features and atmospheric conditions