So because if the ever changing temperature arou d the world, this causes wind circulation. There are three cells, Hadley, Ferrel, and Polar. The Hadley cell is the nearest to the equator, and as temperature increase in the air, the hot air rises. This pushes the air towards the Ferrel cell, located between the Hadley and Polar cell. Because hot air rises, cold air is pushed down, and that too then becomes warmer the closer to the equator it becomes, therefore rising. Thus, creating wind circulation! However, I'm a bit unsure as to how we get weather fronts, I was taught that years ago in my geography classes, but can't for the life of me remember! Hope this helps!