WOTD:Solstice: when the tilt of the Earth's axis is pointing toward or away from the Sun

Equinox: When the earth is not tilted toward or away from the sun, and the hours of daylight and night are equal…

L.T: I can explain why we have seasons

DO NOW: ON WORKSHEET!HW: Seasons Worksheet

Ms. Ware ~ Earth Science ~ 11/16/09

Seasons

What causes the seasons?

http://nix.ksc.nasa.gov/info

What Causes Earth’s Seasons?• Earth’s axis is tilted 23.5 degrees – it always

points in the same direction (Polaris, the North Star) as we orbit our Sun once a year

• This tilt causes the seasons!

http://www.lpi.usra.edu/education/skytellers/seasons/about.shtml

Insolation: INcoming SOLar raDIATIONMore daylight hours, more direct sunlight

Northern Hemisphere Summer

http://www.lpi.usra.edu/education/skytellers/seasons/about.shtml

Animation

• http://esminfo.prenhall.com/science/geoanimations/animations/01_EarthSun_E2.html

Earth’s orbit is almost a perfect circle• Perihelion: When Earth is CLOSEST to our Sun (91 million miles) in winter—January 3

• Aphelion: When Earth is farthest from on our Sun (94 million miles) in summer –July 4

Figure 6h-6: During the equinoxes, the axis of the Earth is not tilted toward or away from the Sun and the circle of illumination cuts through the poles. This situation does not suggest that the 23.5 degree tilt of the Earth no longer exists. The vantage point of this graphic shows that the Earth's axis is inclined 23.5 degrees toward the viewer for both dates (see Figures 6h-3 and 6h-4). The red circles shown in the graphic are the Arctic Circle.

C. The four seasons do not occur in the tropics. These areas receive nearly direct sunlight year-round, so temperatures are high and consistent throughout the year.

DRAWING TIME!!! 15 mins• In groups color and label your seasons diagram….then answer the questions below:

• 1.)Draw the Equator (red crayon)• 2.) Draw tropic of cancer (23.5 N) and tropic of capricorn (23.5 S)

• 2.) Label the summer and winter solstice• 3.) Label the vernal (spring) and fall (autumnal) equinox• 4.) Draw light from the sun (yellow) ~Hint the light should only be able to hit ½ of the earth at once

Answer these questions:

1.) What causes the seasons?2.)Why is it hotter in the Northern Hemisphere at position A on your worksheet?3.) At the equator, there are no summers or winters, only wet and dry seasons. Why is this so?4.)If the earth were not tilted in its orbit, how would the climate and seasons be affected?

Final Summary: Answer these questions in your notebook

• What causes the seasons?• Why is it hotter in the Northern Hemisphere

at position A on your worksheet?• At the equator, there are no summers or

winters, only wet and dry seasons. Why is this so?

• If the earth were not tilted in its orbit, how would the climate and seasons be affected?

How is it that Alaska is dark from…

November 18th- January 23rd

NEW PROBLEM!!!! AHHHH!!!