What is the relationship between a front and cloud formation? Here's a little more info
When conditions are right, two air masses can come together and make a tornado. A humid and warm air mass from the south meets a cold and dry air mass from the north, and the cold air moves under the warm air. This creates a low pressure area, drawing air up and in. The air rotates as it rises, gathering speed and forming a funnel.

Cold air is more dense than warm air, so when a warm air mass meets a cold air mass, the cold air ends up below the warm air. Once the air has risen, it cools and clouds can form. Weather fronts can cause clouds to form.

Weather fronts can cause clouds to form. Fronts occur when two large masses of air collide at the Earth's surface. Warm fronts produce clouds when warm air replaces cold air by sliding above it.

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