Multiple Storm Cloud Behavior (IMAGE) University of Copenhagen Caption In an area with more clouds, the colder, denser air under them, caused by the rainfall, extends downwards and outwards from the cloud. A gust front is formed, and collides with fronts from other clouds. The air is subsequently forced upwards, and a new cloud is formed by the rising air. Credit Søren Granat Usage Restrictions None License Licensed content Disclaimer: AAAS and EurekAlert! are not responsible for the accuracy of news releases posted to EurekAlert! by contributing institutions or for the use of any information through the EurekAlert system.