If the sea is flat, why can't we see 1,000 miles on a really clear day?
First of all, air is not transparent. Secondly light has been observed to bend upwards.
First of all, the gas which makes up air is largely transparent. That's why we can see stuff numb nuts. On a clear day the limiting factor to the distance of observation is the horizon and not the opaqueness of the air.
Secondly... lol whut? Light doesn't bend.
Think about it - there are billions of particles between your eyes and 1000 miles away. Therefore, the parts of the air that are not transparent accumulate and that impairs vision. And, as far as I can tell, most of the flat-earthers (which I am not a part of) on here believe that the earth has peaks and troughs.