Presentation is loading. Please wait.

Presentation is loading. Please wait.

Why do we have seasons?

Similar presentations

Presentation on theme: "Why do we have seasons?"— Presentation transcript:

1 Why do we have seasons?

2 What Causes the Seasons?
The 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. Varying amounts of sunlight create seasons The Earth’s AXIS is the most important reason we have seasons

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

6 Why is it colder in winter, and warmer in summer?
Rays hit Earth at a steep angle Earth leans toward the Sun in summer Hemisphere tilted toward the Sun Winter Rays hit at a shallow angle Rays are more spread out minimizing energy to Earth Less daylight and longer nights

7 Solstices 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 21st The Summer Solstice is the longest day of the year - June 21

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

9 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 winter

10 Winter – Indirect sunlight
Summer – Direct sunlight

11 Seasons…in a nut shell

12 Review Look closely at where the Sun is hitting the Earth during each season:





17 Finish notes paper

Download ppt "Why do we have seasons?"

Similar presentations

Ads by Google