Module 5

• The light rays that are hitting the earth at 90 degrees are known as direct rays

  
• Because the Earth is curved, not all rays hit it directly
• Direct rays


  Light rays that hit the earth at a perpendicular angle

  
• Indirect rays


  Light rays that hit the earth at an angle

  
• Areas of the Earth that are hit by direct rays are warmer than areas that are hit by indirect rays

  
• The equator is always hit by direct rays of the sun

  
• The poles are always being hit by indirect rays
• The tilt of the Earth's axis affects the length of daytime
• The table shows the time of sunrise and sunset on a selected day of each month of the year 2011

  
• Earth rotates on its axis
• Earth's axis is tilted 23.5 degrees
• Because of this tilt and Earth's revolution around the Sun, there is a time when Earth's poles, namely North and South are facing toward or away from the Sun

  
• Earth's rotation causes day and night
• Daytime for any given location on Earth occurs when it is facing toward the Sun

  
• Night time occurs as that location on Earth is facing away from the Sun
• When North pole is facing toward the sun, days are longer in the summer and shorter in the winter
• The equator experiences the least change in the number of daylight hours throughout the year

  
• The Earth's axis is tilted by 23.5 degrees
• The length of daytime varies from month to month due to the tilt of the Earth's axis
• The Earth's axis is not perpendicular to the plane of its orbit
• The Earth is tilted toward the sun in summer, causing longer daylight hours

  
• Locations near the equator experience the smallest change in day length between summer and winter
• Direct rays hit the ground in a straight line and at a 90 degree angle
• Indirect rays, such as diagonal and oblique rays, do not hit the ground directly
• The lengths of days and nights are not equal, they change from month to month
• The equator is warmest because it receives direct sunlight
• The Earth's rotation causes day and night
• Sunrays are direct and indirect, with direct rays hitting Earth at a perpendicular angle

  
• The tilt of the Earth's axis causes variations in the length of daytime