Warm air moves over cold air and replaces it.
A front forms. The type of front depends on which air mass is advancing. If the cool air mass advances, it is a cold front. If a warm air mass advances, it is a warm front. If neither advances, it is a stationary front.
a warm front
a warm front
A warm front forms.
cold front
A warm front forms.
It forms a warm front. Along with this nimbostratus, altostratus, cirrostratus and cirrus clouds are formed.
A front forms. The type of front depends on which air mass is advancing. If the cool air mass advances, it is a cold front. If a warm air mass advances, it is a warm front. If neither advances, it is a stationary front.
A warm front.
a warm front
a warm front
A warm front forms.
It is a warm front.
A warm front forms.
A warm front forms.
A warm front forms.
A warm front forms.