What happens when a warmer

air mass pushes a cooler

air mass?

Formation of Warm front happens when warmer air mass pushes a cooler air mass.

Explanation:

When warm air mass converged or coalesced with cold air mass then there is formation of fronts. Warm air front is gentle sloping front when two air masses move towards to each other warm and moist air aggressively then actively overrides the cold air front then the resultant front is Warm air front. Weather associated to Warm fronts happens when sky is overcasted with the Nimbostratus clouds, moderate rainfall, mild weather and so on.