Energy_and_Matter_in_the_Atmosphere

Energy and Matter in the Atmosphere

• Overview of Physical Geography

  • Course: Geography 102

  • Institution: Fullerton College

Earth-Sun Relations

• Revolution of Earth

  • Earth's revolution around the Sun takes 365 ¼ days.

  • Orbital properties include:

    • Elliptical Orbit:

      • Aphelion: 152,171,500 km (farthest from the Sun)

      • Perihelion: 147,166,480 km (closest to the Sun)

      • Average distance from the Sun: 149,597,892 km

      • Earth travels at a speed of 107,280 km/h (66,660 mph).

    • Earth is at perihelion during Northern Hemisphere winter and aphelion during summer.

  • Distance from the Sun does not significantly affect solar energy received.

Orbital Properties

• Orientation and Tilt

  • Earth's axis is tilted at 23.5°.

  • The plane of the Earth's orbit (ecliptic) is not parallel to the equatorial plane.

  • The Earth maintains polarity; the North Pole always points toward Polaris (North Star).

The Annual March of the Seasons

• Key Conditions

  • Declination of the Sun: Sun's latitude shifts throughout the year.

  • Location of Subpolar Point: The point on Earth where the Sun is directly overhead.

  • Solar altitude and Length of day vary throughout the year due to axial tilt.

  • Solstices:

    • June solstice

    • December solstice

  • Equinoxes:

    • March equinox

    • September equinox

Significance of Seasonal Patterns

• Solar rays spread differently in various latitudes:

  • Tropical latitudes remain consistently warmer.

  • Polar regions are consistently cooler.

  • Midlatitudes experience significant seasonal temperature variations.

Intensity of Sunlight

• Solar Radiation Reception by Latitude

  • Direct and indirect rays impact different geographical areas, influencing climate.

Radiation and the Heat Balance of Planet Earth

• Description and Sources

  • Radiation from the Sun is essential for the Earth's heat balance.

Basic Heating and Cooling Processes

• Radiation

  • Defined as the emission of electromagnetic energy from an object.

  • Warmer objects radiate more effectively and at shorter wavelengths.

  • The Sun is the ultimate "hot" body in the Solar System.

Albedo

• Reflectivity of an object

  • Light colors reflect; dark colors absorb.

Absorption and Reflection

• Absorption

  • Objects absorbing radiation behave as good radiators.

• Reflection

  • Electromagnetic waves are repelled by objects.

Greenhouse Effect

• Atmospheric Mechanism

  • Some gases transmit shortwave radiation, trapping Earth’s longwave radiation, creating a greenhouse effect.

Other Heating Types

• Conduction

  • Transfer of heat energy through molecular collisions; air is a poor conductor.

• Convection

  • Vertical heat transfer by circulation; occurs in convection cells.

  • Advection: Horizontal heat transfer in fluids.

Composition and Structure of the Atmosphere

• General Structure

  • Atmosphere surrounds the Earth, held by gravity up to 10,000 km.

  • Over 50% of mass is below 6 km.

Contents of the Atmosphere

• Constant Gases:

  • 99% are nitrogen (78%) and oxygen (21%).

• Variable Gases:

  • Above 100 km: carbon dioxide, water vapor, ozone.

  • Aerosols, including particles, play a role in cloud formation and atmospheric color.

Vertical Structure of the Atmosphere

• Thermal Layers:

  • Troposphere: Lowest 10-15 km; weather occurs here.

  • Stratosphere: Stagnant air layer.

  • Mesosphere: Middle atmospheric layer.

  • Thermosphere and Exosphere: Transitional spaces to outer space.

Air Pressure

• Decreases with height; more compressed at lower levels.

Temperatures of the Lower Atmosphere

• Global Temperature Distribution:

  • Visual representation of average temperatures at various latitudes.

Energy, Heat, and Temperature

• Definitions:

  • Temperature: Average kinetic energy of molecules in a substance.

  • Heat: Energy transferred due to temperature differences.

Basic Heating and Cooling Processes

• Adiabatic Cooling/Warming

  • Cooling: Air rises and expands, reducing molecular collision and lowering temperature.

  • Warming: Sinking air compresses and increases molecular collisions, raising temperature.

North Pole Energy Budget

• Describes energy surplus and deficit relationships across different latitudes.

Land and Water Contrasts

• Heating and Cooling Dynamics:

  • Land heats and cools faster than water due to differences in specific heat, transmission, mobility, and evaporative cooling.

Implications of Contrasts

• Temperature Examples:

  • Dallas (32° 51' N): Avg temp 18°C (65°F)

  • San Diego (32° 44' N): Avg temp 17°C (63°F)

Daily Radiation Curves

• Temperature Variations:

  • Daily temperature fluctuations, with coolest times around midnight and warmest at noon.

Mechanisms of Heat Transfer

• Circulation Patterns:

  • Atmospheric and oceanic patterns are crucial for energy distribution between tropics and poles.

Deep Ocean Circulation

• Driven by density differences, affected by ocean temperature and saltiness.

  • Cold, dense Arctic waters mix with Gulf Stream waters, forming sinking North Atlantic Deep Water.

Global Temperature Patterns

• Primary Controls:

  • Temperature affected by latitude, wind patterns, ocean currents, land-water contrasts, and altitude.

  • Illustrates average temperature distributions in January and July.