Global Heat Balance

Overview

• Aristotle classified Earth's heat zones despite inaccuracies; his classification is generally accepted.
• Three main heat zones:
  • Torrid Zone
  • Temperate Zone
  • Frigid Zone

Earth's Heat Zones

Torrid Zone

• Located between the Tropic of Cancer and the Tropic of Capricorn.
• Receives maximum insolation and is hotter due to concentrated heat.
• Has more insolation during the day than terrestrial radiation lost at night.
• Inquiry Question: If more insolation is received than terrestrial radiation lost, won't this zone keep heating?

Temperate Zone

• Northern Temperate Zone: Between Tropic of Cancer and Arctic Circle.
• Southern Temperate Zone: Between Tropic of Cancer and Antarctic Circle.
• Experiences different seasons: spring, summer, autumn, winter.
• Northern Zone: Europe, Northern Asia, North and Central America.
• Southern Zone: Southern Australia, South America, Southern Africa.

Frigid Zone

• Receives very little insolation due to sun's angle; sometimes no sun rays are received.
• Insolation received is less than terrestrial radiation given out.
• Inquiry Question: How does this region emit more energy than it receives?

Changes in Temperature

Daily Temperature Cycle

• Day: Earth receives insolation, heating gradually increasing to max around 3 pm.
• Morning: Sun's slanting rays spread insolation over a larger area, leading to low temperatures.
• Noon: Sun's rays cover a smaller area, temperature increases gradually, peaking between 2-3 pm.
• Evening: Slanting rays indicate decreasing temperature.
• Night: No insolation, temperature decreases; coldest just before sunrise due to radiated heat.