As the air becomes warmer and drier while it moves down the leeward side of the mountain, the orographic effect takes place. This effect will then further lower the humidity of the leeward side-bound air and loses moisture even faster.
When air becomes warmer and drier as it moves down the leeward side, it rises up the atmosphere.
When the air moves from the windward to the leeward side, that is when the air moves downward, it becomes warm very rapidly and loses all of its moisture content, and thereby becomes dry. This results in the formation of a very high kind of wind which is commonly known as Chinook (or Foehn) winds. This type of wind has a higher temperature and occurs when high mountain ranges are oriented perpendicular to the direction of prevailing winds. For example, the Sierra Nevadas occurring in North America.
If there was no sun, the weather on earth would drastically change. There would be no natural source of sunlight so it'd be very cold without the sun and it would always be "night time" because there is no sun to give daylight meaning that it is dark.
