On satellite, it can be easy to find the clouds and clear regions but more difficult to determine cloud height and type. Cloud height can be inferred by the cloud temperature on infrared imagery. A good idea is to divide the troposphere up in your mind into three layers: low levels (surface to 700 mb), middle levels (700 mb to 500 mb) and upper levels (above 500 mb). Low clouds on Infrared imagery will have a darker shade since they are relatively warm. In fact, clouds that are about the same temperature as the surface can be very difficult to detect. Thus, low clouds are pretty easy to determine by looking at infrared imagery if they have a different temperature as compared to the ground surface. The middle level clouds will be colder and thus more white on infrared imagery. Sometimes it can be difficult to distinguish between a middle and upper level cloud, with the exception of thunderstorms. When the cloud is a thunderstorm or thunderstorm complex it is very noticeable since the cloud tops are very cold with overshooting tops and cirrus blow-off. Thus, the tops of thunderstorm clouds are easy to notice on satellite. Here are how the different cloud types look on satellite imagery: Fair Weather Cumulus: A darker shade on infrared imagery since they are close to surface. On visible they look like a field on white bubbles with space between each white blob. Since this clouds have plenty of moisture they are usually fairly white on visible. Low level Stratus: Dark on infrared since these clouds are relatively warm. They often spread over a wide area. On visible they are fairly reflective and thus fairly white. Since they are stratus clouds they have a much smoother appearance as compared to thunderstorm clouds. Altostratus / Nimbostratus: They are colder than low level stratus thus they are whiter on infrared imagery. They are fairly white on visible imagery. Altocumulus: Look similar to altostratus but are more globular. Thunderstorm Clouds: Very bright white on infrared and visible imagery since the cloud tops are very cold and the clouds are very thick. They are texture on visible due to the shadows being cast. Overshooting tops show up very cold on infrared. Often an anvil with anvil blow off from the upper level winds can be seen. Cirrus: Just like they look wispy in person from the ground they can look thin and wispy on visible imagery also. If the cirrus are thin enough they might not be seen at all on satellite imagery. Cirrus clouds are very cold. However, since they are often thin also they sometimes do not show up on infrared as well as one might think. If they are thick though they will show up very well on infrared as bright white clouds. Fog: Often has edges along elevated surfaces on visible imagery and often forms over wet areas. Fog likes to develop in valleys. On infrared it can be difficult to see since the temperature is about the same as the surface. On visible though they will be white like any other clouds. |