美国内布拉斯加州上空的乳状云

2023年2月12日

Mammatus Clouds over Nebraska
Image Credit & Copyright: Jorn Olsen Photography

Explanation: 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 pockets 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.

Tomorrow’s picture: comet mars

美国内布拉斯加州上空的乳状云
图像提供与版权: Jorn Olsen Photography

说明: 何时云底会形似泡泡呢？正常的云底是平的；这是因为潮湿的暖空气上升，通常会在某个特定温度及其对应的特定高度，冷凝而结成小水滴。接着在小水滴变大之后，就形成不透光的云。不过，在某些情况下，云的某些区域会发展出含有大水滴或冰粒的云胞，然后向下沈降并蒸发。这种云胞可能出现在雷暴系统的湍流区附近，所形成的乳状云在阳光的侧照之下，看起来格外醒目。上图的乳状云，是在2004年6月摄于美国内布拉斯加州黑斯廷斯市的天空中。

明日的图片: comet mars