A front is the boundary at the ground between two air masses of different temperature and humidity. At a cold front, cold air pushes into warmer air and takes its place; at a warm front, warm air pushes into colder air and takes its place.
উদাহরণ
Example 25.7 (Reading a barometer’s record)
For the first 8 hours the pressure rises to about : the anticyclone passes over S, with settled weather. Then it falls for 30 hours, by about : the depression is coming. It falls fastest a few hours before the warm front passes, more slowly in the warm air behind it, and reaches its lowest, about , just as the cold front passes. Then it rises: the depression is moving away, and the cooler, clearer air behind the cold front arrives.