Day & Night

The Earth spins on its axis

• The spinning is called ROTATION

• The direction of rotation is counterclockwise if you are looking at it as if you were floating over the North Pole

http://vortex.plymouth.edu/sun/sun.html

As the Earth spins, part of the Earth is facing toward the Sun,

and part is facing away from the Sun.

The part of the Earth facing the Sun has daytime

Because the Earth is tilted, different parts of the planet get different amounts of sunlight at

different times of the year.

http://ithacasciencezone.com/earthzone/lessons/07meteor/daylight.jpg

In the Spring and Fall

http://k12.ocs.ou.edu/teachers/reference/equinox.gif

EQUINOX

A day lasts 12 hours and a night

lasts 12 hours at all latitudes.

Sunlight strikes the earth most directly

at the equator.

In the Summer and Winter

http://k12.ocs.ou.edu/teachers/reference/solstice.gif

SOLSTICEDuring the winter the Northern Hemisphere day lasts fewer

than 12 hours and the Southern Hemisphere day lasts

more than 12 hours.During the winter solstice, the North Pole has a 24-hour night and the South Pole has a 24-

hour day.Sunlight strikes the earth most

directly at the Tropic of Capricorn.

In the Summer and Winter

http://k12.ocs.ou.edu/teachers/reference/solstice.gif

SOLSTICE During the summer solstice the Northern Hemisphere day lasts

more than 12 hours and the Southern Hemisphere day lasts

fewer than 12 hours.During the summer, the North

Pole has a 24-hour day and the South Pole has a 24-hour night.

Sunlight strikes the earth most directly at the Tropic of Cancer.

Let’s look at some more computer models:

http://ithacasciencezone.com/earthzone/lessons/07meteor/daynight.htm

What about San Antonio?

Notice our latitude

Notice the latitude of the Tropic of Cancer.

Bexar County

How does living so close to the Tropics affect out day length