Fact 1: The movement of an air mass over Earth 's surface causes local weather changes.

Fact 2: Weather is the condition of the atmosphere.

Given the two facts above, answer the question "What movement causes local changes to the condition of the atmosphere?" with the following options: 
- air mass over the moon
 - air mass under Earth's surface
 - a hemisphere is tilted away from the sun
 - energy of moving objects
 - air mass over Earth's surface
 - pressure differences.
 - wind and erosion
 - core mass under Earth


 

     air mass over Earth's surface    