What causes changes in weather? a. air masses move and meet. c. water evaporates. b. the air gets more humid. d. clouds form.

Air masses move and meet

Explanation:

The formation, movement, and collision of the air masses is one of the biggest and most noticeable changer of the weather conditions, be it locally, regionally, or globally. The air masses are constantly on the move, with the basic rule being - the heavier, denser air masses move toward the less dense, lighter air masses. Once they come in contact, the denser, heavier air masses push upward or backward the less dense, lighter air masses. The properties of the air masses depend on the place they have formed, so they can be dry, wet, cold, warm, and they are able to change the weather conditions literary in several minutes.

indicate valleys, hills, steepness and gentleness of slopes.

explanation:

contour lines on a map indicate elevation, or depth. numeric notations on contour lines refer to the level of elevation, or height about sea level.