A cold front forms when a cold air mass replaces a warm air mass. Which boundary is this?

A cold front forms when a cold air mass replaces a warm air mass. Which boundary is this?

• A. Warm front
• B. Cold front
• C. Stationary front
• D. Occluded front

Answer: (B)

A cold front is the boundary formed when a cold air mass advances into and replaces a warmer air mass. The leading edge of that advancing cold air pushes the warmer air upward, causing vertical development of clouds and often showers or thunderstorms along or ahead of the front. After the passage, temperatures drop quickly and the air tends to become cooler and drier, sometimes with gusty winds. This boundary differs from a warm front, where warm air slides over colder air leading to more gradual, longer-lasting precipitation and a warming trend. It isn’t a stationary boundary, which would mean little movement, and it isn’t an occluded front, which occurs later when a fast-moving cold front catches up to a slower warm front and lifts the warm air off completely.

A cold front is the boundary formed when a cold air mass advances into and replaces a warmer air mass. The leading edge of that advancing cold air pushes the warmer air upward, causing vertical development of clouds and often showers or thunderstorms along or ahead of the front. After the passage, temperatures drop quickly and the air tends to become cooler and drier, sometimes with gusty winds.

This boundary differs from a warm front, where warm air slides over colder air leading to more gradual, longer-lasting precipitation and a warming trend. It isn’t a stationary boundary, which would mean little movement, and it isn’t an occluded front, which occurs later when a fast-moving cold front catches up to a slower warm front and lifts the warm air off completely.