On an "extreme clear" (pilot lingo) day, how far is it from the point where you stand to the horizon?

Question

I saw a reference to this in a weather program, but no indication was made as to how far each of us is from the horizon that we observe. Any info would be appreciated.

Answer 1

The curvature of the earth prevents you seeing very far. If you were stood on the edge of an ocean and looked out across the water you would be able to see for about 4.8 kilometres (3 miles).

If you were on a 1000 metre high hill and there was nothing blocking your line of sight you would see much further - 114 kilometres (71 miles).

There's a formula you can use - the square root of the product of 13 times the height of the observer in metres. For example, height of observer is 200 metres, 13 x 200 = 2600, sqrt of 2600 = 50.990 kilometres.