Ravi

Another good, easy test for evaluating a dark sky site is to look at the night time clouds. If they are illuminated from underneath by local light pollution sources then the sky will not be as dark as it could be.

In the ideal situation clouds will appear as black shapes against a fairly bright night sky. This video from my observing site sort of illustrates the point- the clouds are noticably darker than the sky behind them, indicating low local light pollution.

From the same site really high clouds (~35,000 feet) actually pick up light pollution from towns 60-80 miles further south.

This contrail drifting through M8 and M20 in Sagitarius is clearly illuminated by distant sodium street lights.

Thanks for the video it was better than a thousand words!