Day-Night Globe -- What is Going On?

Think of what you have done or plan to do:

1.    You placed your Day-Night Globe in direct sunlight.
2.    You oriented it such that
        a.    Your location on the globe is at its very top; and
        b.    Its north pole points toward the true geographic north.

What does this accomplishes?

Sun rays hit Your DNG exactly the same way they are hitting planet Earth at the very same time!

Click on Image to see large image (67KB)

So What?

The illuminated half of the sphere shows the Earth's half where is now daytime.

The shaded half of the sphere shows the Earth's half where is now nighttime.

The area where shade and light meet are where right now dawn and dusk are happening.

Dawn is where shade is west of the light.

Dawn is approaching the Far East

Dusk is where light is west of the shade.

As the earth rotates eastbound the sunlit areas on both Earth and your DNG move toward the west.
If you wait till dusk, you will see the dusk area on your globe.

By the sea. If you can do this on a seashore where sunrise or sunset takes place, you will see a more pronounced difference between daylight and night on your DNG.

Feel the temperature difference. After your DNG has stood in the sun for a while, the illuminated surface is much warmer than the shaded surface.

More subtle temperature differences exist even on the surface of the illuminated half of the DNG. They are the result of the angle at which sunlight hits the surface.

In October daylight in Antarctica lasts longer and longer.
However, because of the differnce in the angle of incidence between
the equator and Antarctica, Antarctica is much cooler than the tropics.

Position yourself such that the globe is between you and the sun (so you do not cast a shadow on the globe) and your eyes are exactly above your location -- a high-flying pilot point of view.

Pay attention to the reflection of the sun on the surface of the DNG.

* The longitude (meridian) of this reflection is the one above which the sun is currently located.

Now Try This:

1. Move your head vertically, exactly (as best you can) above your location.

Notice that while you do so, the reflection of the sun on the globe moves along the same longitude.

2. Move your head from side to side or in any angle.

Notice that while you do so, the reflection of the sun on the globe moves all over the surface.

Can you explain the reason for the difference?

Can you move your head such that the sun reflection remains stationary?

Look at the poles.

If it is summer in the Northern Hemisphere the North Pole is illuminated. If you rotate the DNG around its axis, you will see that there is no night at the North Pole. At the South Pole there is long night.

If it is summer in the Southern Hemisphere the South Pole is illuminated. If you rotate the DNG around its axis, you will see that there is no night at the South Pole. At the North Pole there is long night.