Cloud top

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The cloud top is the highest visible part of a cloud. It’s measured in meters above the ground or in the corresponding air pressure. The top often tells us where precipitation like rain or snow comes from.

There are several ways to work out cloud top height:
- Ground triangulation for isolated clouds.
- Ground-based radar.
- Airborne methods, including visual checks or lidar, which are good for single clouds but not practical over large areas.
- Satellite methods: stereo photography from different angles (using instruments like MISR or ATSR) or estimating height from measured temperatures.
- Real-time cloud top pressure maps from GOES satellites.

Convection (the strong rising of warm, moist air) largely shapes cloud tops in stormy clouds, and this depends on heat and moisture supplied from the surface. Cloud tops can vary a lot, more than the cloud bases do.

Clouds affect radiation in two ways: they change how much sunlight is reflected (albedo), depending on particle size and height; and in the infrared, water in clouds absorbs and emits energy. Higher cloud tops are cooler and emit less infrared radiation.