The triangles point away from the colder air while the semi-circles point away from the warmest air. A cold front is a front that is moving in the direction of the warmer air. A cold front is indicated on the line by blue triangles pointing away from the colder air. A warm front is a front that is moving in the direction of the colder air. A warm front is indicated on the line by red semi-circles pointing away from the warmer air.
Warm air is lifted and clouds can form if enough water vapor is present.
Warm air lifts over cold air and clouds can form if enough water vapor is present. Symbols on fronts, such as blue triangles for cold and red half circles for warm are always drawn and pointing in the direction in which the air is advancing.