Consider the following statements:

1. During the day, heated mountain slopes cause air to move upslope, while air from the valley flows upward as a valley breeze.
2. At night, cooled slopes produce descending dense air known as a mountain wind.
3. Cold air draining from high plateaus and ice fields into valleys is called katabatic wind.
4. Air descending the leeward side of a mountain becomes cooler through the adiabatic process.

Which of the statements given above are correct?