Earth's Energy Budget

• Earth receives only a very small portion of the sun’s energy, yet this energy is responsible for powering the motion of the atmosphere, the oceans, and many processes at Earth’s surface.
  • About one-third of the sun’s incoming energy is reflected back out to space.
  • About one-half of the energy striking Earth is absorbed by Earth’s surface.
  • Solar radiation is made up of different types of radiation (including infrared, visible light, and ultraviolet).

Greenhouse Effect

• Incoming solar radiation is in close balance with the energy that leaves the atmosphere; otherwise Earth would heat up or cool down.
  • Excess carbon dioxide and other gases may disrupt this balance, creating a greenhouse effect.

Radiation and Convection

• Earth’s surface is heated unequally.
• When air or water is heated, the molecules move faster and farther apart, reducing their density and causing them to rise.
• Cooler air or water molecules move more slowly and are denser than warm air or water.

• Warm air or water rising coupled with cooler air or water descending forms a cyclic rising/falling pattern called convection.
  • Radiation and convection from Earth’s surface transfer thermal energy.
  • This energy powers the global circulation of the atmosphere and the oceans on our planet.

Clouds and Weather

• Clouds: As bodies of water (oceans, lakes, rivers, etc.) absorb thermal energy, the water evaporates causing the air to be warm and moist.
  • Warm, moist air is less dense than cold, dry air, so it rises relative to colder, drier air.
  • As warm, moist air rises, it gives off some thermal energy as the moisture condenses, forming clouds.
  • Clouds are not gaseous water vapor; rather they are minute, condensed water particles.
• Some thunderstorms are formed where the land is strongly heated.
  • Hurricanes form over warm, tropical water and are fed by the energy of that water.
• Do you know the following terms as they relate to solar energy: wavelength; ultraviolet, visible, and infrared radiation; and reflection and absorption?
• Can you explain the chart on Earth’s energy budget?
• Can you explain the greenhouse effect in terms of the energy entering and leaving the atmosphere?
• design an investigation to determine the effect of sunlight on the heating of a surface.
• analyze and explain how convection currents occur and how they distribute thermal energy in the atmosphere and oceans.
• analyze the role of heating and cooling in the formation of clouds.
• order the sequence of events that takes place in the formation of a cloud.
• describe the relationship between thermal energy and the formation of hurricanes and thunderstorms.