[自贸港英语]NASA：海南夏季午后的清凉雨

夏季的海南，越是特别闷热的时候，午后往往乌云密布、电闪雷鸣，雷雨过后天空放晴，凉风清新彩霞漫天，为不少初到海南的人们带来惊喜。最近NASA 的地球观测站Earth Observatory网站，通过卫星云图解释了这一美妙的现象。

The south-central part of the island is mountainous, with elevations of more than 1800 meters (5,900 feet) surrounded by plains extending to the island’s northeast. The rugged topography creates orographic lift: when air moves across the plains and encounters the mountains, it is forced upward. So, when moist ocean air moves from low to high elevations, it cools and condenses into clouds.

岛的中南部是山区，海拔超过1800米（5,900英尺），周围是平原，一直延伸到该岛的东北部。崎岖的地形会产生地形上的升力：当空气在平原上移动并遇到山脉时，被迫向上移动。因此，当潮湿的海洋空气从低海拔移动到高海拔时，它会冷却并凝结成云。

elevation：海拔

moist：潮湿的

condense：凝结

The terrain enhances the convection. But even if the island were completely flat, cumulonimbus could still develop, as the collision of air masses also forces air upward. Starting in the morning, the Sun quickly heats up the land and warms the air above it. The warm air rises it leaves behind a pocket of low pressure. Air within high pressure areas over the ocean moves in to fill the void, producing an onshore wind known as a “sea breeze.”

地形增强了对流。但是即使该岛完全平坦，积雨云仍可能发展，因为气团的碰撞也迫使空气向上。从早晨开始，太阳迅速加热土地并加热其上方的空气。温暖的空气上升，形成低压区域。海洋高压区域内的空气进入以填充空隙，从而产生一种被称为“海风”的陆上风。

enhance：增强

collision：碰撞

As the cool, moist air from over the South China Sea moves toward the island’s interior, it can collide with warm air along the sea breeze front. The cool air forces the less dense warm air to rapidly rise, producing the vertical towers of clouds. Convection can be particularly intense in areas where sea breezes from opposite sides of the island ultimately collide.

当来自南中国海的凉爽潮湿的空气流向岛内时，它会与海风前沿的温暖空气相撞。冷空气迫使密度较小的暖空气迅速上升，从而形成垂直的云塔。在该岛相对两侧的海风最终发生碰撞的区域，对流可能特别强烈。

vertical：垂直的

Convection：对流

ref：https://earthobservatory.nasa.gov/images/146761/cloud-building-over-hainan