Earth's Orbit and Rotation

Key Concepts

• Earth orbits the Sun, completing one full orbit in a year.
• Earth rotates on its axis, tilted like a spinning top.
• The tilt remains consistent throughout the orbit, affecting sunlight exposure.

Seasonal Changes

Winter in the Northern Hemisphere

• North Pole tips away from the Sun.
• Sunlight strikes the Northern Hemisphere at a shallow angle.
• Results in:
  • Cool winter weather.
  • Short days and long nights.

Transition to Spring

• Earth tilts neither toward nor away from the Sun.
• Day and night are approximately equal in length.

Summer in the Northern Hemisphere

• North Pole tips toward the Sun.
• Sunlight strikes the Northern Hemisphere more directly.
• Results in:
  • Warmer temperatures.
  • Longer daylight hours compared to winter.

Seasons Reversed

• While it's summer in the Northern Hemisphere, it is winter in the Southern Hemisphere due to Earth's tilt.

Impact on Life

Primary Producers

• Plant life and photosynthesizers depend on sunlight.
• Changes in seasons affect their productivity.

Carbon Dioxide Absorption

• Earth orbiting satellites measure CO2 absorption by primary producers.
• Bright regions on maps indicate areas with high carbon dioxide absorption.

Ocean Productivity

• In spring, sunlight warms cold waters, leading to a spike in productivity.
• Phytoplankton and other photosynthesizers form the basis of the ocean food web.

Land Productivity

• Forests grow lush in spring, brightening continents.
• During winter, continents appear dark due to reduced photosynthesis.