Meriden ARC Web Site | Castle Craig Chapter 10-10


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Twilight Definitions
#1
As I learn new things about the information on the weather page of my WX Station I found these definitions of Twilight from an Australian Web Page

Definitions

Civil twilight

This occurs after sunset or before sunrise when the centre of the sun is up to 6° below the horizon. At this time the brightest stars are normally visible, and under good weather conditions terrestrial objects will still be visible.

Nautical twilight
This occurs when the sun is between 6° and 12° below the horizon. At this time only the general outlines of ground objects may be visible, but the horizon is still visible, even on a moonless night.

Astronomical twilight
This occurs when the sun is between 12° and 18° below the horizon. There is no colour in the sky during astronomical twilight, and it is not possible to make out the horizon.

Al - N1API
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