The French league had different values at different times: 10 000, 12 000, 13 200 and 14 400 French feet, about 3.25 km to about 4.68 km. It was used for a while together with the metric system but it is not used now. The nautical league was three nautical miles.
Why does precipitation fall mainly on the windward side of a mountain? When humid winds blow from the oceans toward mountains they must rise up to pass over the mountains. The rising warm air cools when it rises and its water vapor condenses, forming clouds rain or snow falls on the windward side of the mountain. microclimate Climate within a small area that differs significantly from the climate of the surrounding area
This is because the constant tradewinds carry rainclouds onto the windward parts of the islands, but the mountains on the island keep the rainclouds from going to the leeward parts. The windward half of each island is green and forested, the leeward half is more dry. So people living in Hawaii often use leeward and windward to give directions around the islands. It's pretty obvious which way is which when you're there.