Which type of front occurs when cold air and warm air are next to each other but are at a a stand still ?

Stationary front

Explanation:

A stationary front is usually defined as a front that forms when the cold and warm air masses are next to each other but are at a standstill. This normally takes place when both the air masses push one another but neither of them is sufficiently strong to push the other. Both the air masses remain stationary because the winds blow parallel to the front instead of blowing perpendicular.

This type of front is basically responsible for the formation of cloudy weather that leads to rainfall or snowfall.

This stationary front is usually identified as the alternate red-colored semicircles and blue-colored triangles on weather maps. Both blue triangles and red semicircles are directed in the opposite direction.