Mammatus Clouds over Nebraska.

When do cloud bottoms appear like bubbles? Normally, cloud bottoms are flat . This is because moist warm air that rises and cools will condense into water droplets at a specific temperature, which usually corresponds to a very specific height. As water droplets grow , an opaque cloud forms. Under some conditions, however, cloud pockets can develop that contain large droplets of water or ice that fall into clear air as they evaporate. Such pocket s may occur in turbulent air near a thunderstorm . Resulting mammatus clouds can appear especially dramatic if sunlit from the side. The mammatus clouds pictured here were photographed over Hastings , Nebraska during 2004 June.