1. Why do we have seasons? http://www.youtube.com/watch?v=HlvQ1fVMqNA

2. What Causes the Seasons? http://www.youtube.com/watch?v=q4_-R1vnJyw The earth’s orbit – revolution around the Sun- - is inclined 23.5 degrees from the horizontal plain, is the cause for the change in seasonsThe earth’s orbit – revolution around the Sun- - is inclined 23.5 degrees from the horizontal plain, is the cause for the change in seasons http://www.youtube.com/watch?v=q4_-R1vnJyw The earth’s orbit – revolution around the Sun- - is inclined 23.5 degrees from the horizontal plain, is the cause for the change in seasonsThe earth’s orbit – revolution around the Sun- - is inclined 23.5 degrees from the horizontal plain, is the cause for the change in seasons

3. Earth’s rotation The Earth rotates on its axis (imaginary vertical line around which Earth spins) every 23 hours & 54 minutes.The Earth rotates on its axis (imaginary vertical line around which Earth spins) every 23 hours & 54 minutes. Varying amounts of sunlight create seasonsVarying amounts of sunlight create seasons The Earth’s AXIS is the most important reason we have seasonsThe Earth’s AXIS is the most important reason we have seasons The Earth rotates on its axis (imaginary vertical line around which Earth spins) every 23 hours & 54 minutes.The Earth rotates on its axis (imaginary vertical line around which Earth spins) every 23 hours & 54 minutes. Varying amounts of sunlight create seasonsVarying amounts of sunlight create seasons The Earth’s AXIS is the most important reason we have seasonsThe Earth’s AXIS is the most important reason we have seasons http://www.youtube.com/watch?v=lkWyM- M8o0c

4. Earth’s revolution It takes the Earth 365 days (or rotations) to travel or revolve around the Sun once.It takes the Earth 365 days (or rotations) to travel or revolve around the Sun once. This is called aThis is called a year. year. It takes the Earth 365 days (or rotations) to travel or revolve around the Sun once.It takes the Earth 365 days (or rotations) to travel or revolve around the Sun once. This is called aThis is called a year. year. The Earth ROTATES daily The Earth REVOLVES around the Sun

5. Earth’s Orbit The Earth’s orbit around the sun is NOT a perfect circle.The Earth’s orbit around the sun is NOT a perfect circle. It is an ellipse. It is an ellipse. Seasons are not caused by how close the Earth is to the sun.Seasons are not caused by how close the Earth is to the sun. The Earth is closest to the sun around January 3 and farthest away from the sun around July 4.The Earth is closest to the sun around January 3 and farthest away from the sun around July 4. The Earth’s orbit around the sun is NOT a perfect circle.The Earth’s orbit around the sun is NOT a perfect circle. It is an ellipse. It is an ellipse. Seasons are not caused by how close the Earth is to the sun.Seasons are not caused by how close the Earth is to the sun. The Earth is closest to the sun around January 3 and farthest away from the sun around July 4.The Earth is closest to the sun around January 3 and farthest away from the sun around July 4. Ellipse

6. Why is it colder in winter, and warmer in summer? Summer – Rays hit Earth at a steep angleRays hit Earth at a steep angle Earth leans toward the Sun in summerEarth leans toward the Sun in summer Hemisphere tilted toward the SunHemisphere tilted toward the SunWinter Rays hit at a shallow angleRays hit at a shallow angle Rays are more spread out minimizing energy to EarthRays are more spread out minimizing energy to Earth Less daylight and longer nightsLess daylight and longer nights Summer – Rays hit Earth at a steep angleRays hit Earth at a steep angle Earth leans toward the Sun in summerEarth leans toward the Sun in summer Hemisphere tilted toward the SunHemisphere tilted toward the SunWinter Rays hit at a shallow angleRays hit at a shallow angle Rays are more spread out minimizing energy to EarthRays are more spread out minimizing energy to Earth Less daylight and longer nightsLess daylight and longer nights

7. The AXIS Seasons are the result of the tilt of the Earth's axis. Earth’s axis is tilted 23.5°. This tilting is why we have SEASONS like fall, winter, spring, summer. The number of daylight hours is greater for the hemisphere, or half of Earth, that is tilted toward the Sun. Seasons are the result of the tilt of the Earth's axis. Earth’s axis is tilted 23.5°. This tilting is why we have SEASONS like fall, winter, spring, summer. The number of daylight hours is greater for the hemisphere, or half of Earth, that is tilted toward the Sun.

8. SolsticesSolstices Solstices occur twice a year, when the tilt of the Earth's axis is oriented directly towards or away from the Sun, causing the Sun to appear to reach its northernmost and southernmost extremes.Solstices occur twice a year, when the tilt of the Earth's axis is oriented directly towards or away from the Sun, causing the Sun to appear to reach its northernmost and southernmost extremes. Winter solstice is the shortest day of the year- December 21 stWinter solstice is the shortest day of the year- December 21 st The Summer Solstice is the longest day of the year - June 21The Summer Solstice is the longest day of the year - June 21 Solstices occur twice a year, when the tilt of the Earth's axis is oriented directly towards or away from the Sun, causing the Sun to appear to reach its northernmost and southernmost extremes.Solstices occur twice a year, when the tilt of the Earth's axis is oriented directly towards or away from the Sun, causing the Sun to appear to reach its northernmost and southernmost extremes. Winter solstice is the shortest day of the year- December 21 stWinter solstice is the shortest day of the year- December 21 st The Summer Solstice is the longest day of the year - June 21The Summer Solstice is the longest day of the year - June 21 https://www.youtube.com/watch?v=FmCJqykN2J0

9. Equinoxes A day lasts 12 hours and a night lasts 12 hours at all latitudes.A day lasts 12 hours and a night lasts 12 hours at all latitudes. Equinox literally means "equal night".Equinox literally means "equal night". Sunlight strikes the earth most directly at the equator.Sunlight strikes the earth most directly at the equator. This occurs twice a year.This occurs twice a year. Spring (vernal)– March 21Spring (vernal)– March 21 Fall (autumnal) – September21Fall (autumnal) – September21 A day lasts 12 hours and a night lasts 12 hours at all latitudes.A day lasts 12 hours and a night lasts 12 hours at all latitudes. Equinox literally means "equal night".Equinox literally means "equal night". Sunlight strikes the earth most directly at the equator.Sunlight strikes the earth most directly at the equator. This occurs twice a year.This occurs twice a year. Spring (vernal)– March 21Spring (vernal)– March 21 Fall (autumnal) – September21Fall (autumnal) – September21

10. Summer is warmer than winter (in each hemisphere) because the Sun's rays hit the Earth at a more direct angle during summer than during winterSummer is warmer than winter (in each hemisphere) because the Sun's rays hit the Earth at a more direct angle during summer than during winter

11. The days are much longer than the nights during the summerThe days are much longer than the nights during the summer During the winter, the Sun's rays hit the Earth at an extreme angle, and the days are very short During the winter, the Sun's rays hit the Earth at an extreme angle, and the days are very short These effects are due to the tilt of the Earth's axisThese effects are due to the tilt of the Earth's axis The days are much longer than the nights during the summerThe days are much longer than the nights during the summer During the winter, the Sun's rays hit the Earth at an extreme angle, and the days are very short During the winter, the Sun's rays hit the Earth at an extreme angle, and the days are very short These effects are due to the tilt of the Earth's axisThese effects are due to the tilt of the Earth's axis

12. Seasons…in a nut shell

13. Review Look closely at where the Sun is hitting the Earth during each season: http://www.youtube.com/watch?v=knK87GoNyGo

18. Your assignment is….. https://www.youtube.com/watch?v=10Jzw1hjOv4 https://www.youtube.com/watch?v=82p-DYgGFjI