The Moon with Atmospheric Temperature Variance

This video was made to show what Atmospheric Temperature Variance looks like when viewing the Moon.

But exactly how do temperature variations cause twinkling in stars or making the moon look like it’s under water?

When light enters a transparent medium, such as air, it generally changes direction, i.e. it is scattered. By how much it changes direction, i.e. bent, however, depends on the temperature. Warm air bends light less, while cool air bends more, because in warm air the air molecules are further apart from each other, producing less scattering.

Now any star, except the sun, is so far away that practically, it is sending only a single ray of light towards us. As that ray enters the atmosphere, it is scattered differently as it passes through air of different temperatures. When it is scattered away from us, the star seems to disappear for a moment. When it is scattered into our eyes, it seems to reappear, resulting in a twinkle.