When does a cold front occur?

<p style=";text-align:left;direction:ltr">Arab Weather - A cold front occurs when a cold air mass moves towards a warm air mass. Since cold air is denser, it slides under the warm air and lifts it upwards quickly, leading to the formation of cumulonimbus clouds that may cause thunderstorms or heavy rains in short periods.</p><p style=";text-align:left;direction:ltr"> After the cold front passes, temperatures drop significantly, and the atmosphere becomes drier and colder.</p>