As it rises, it will cool and condense into cloud and rain. This type of rain takes a long time to arrive. Rain begins slowly and remains steady for several hours if not days. The barometric pressure will have been dropping slowly as the front approaches. The rain from a Warm Front is not dependent on the presence or absence of the Sun and can occur at any time of the day or night.
Warm Fronts can occur over land or sea as they are a phenomenon of the atmosphere.
A Cold Front occurs when a cold air mass meets a warm air mass. Again, the two air masses do not mix. The cold air, being more dense, forces its way under the warm air. The warm air is forced up quickly. This leads to large Cumulonimbus clouds giving heavy showers, often with thunder, lightning and hail.