Water Vapor - Real-time

Water Vapor - Real-time thumbnail


Meteorologists use satellite images to observe the current conditions of the atmosphere. There are many different types of satellite images that each reveal different aspects of the atmosphere. One of the images that they use is the water vapor image. Everything emits and absorbs radiation, including water vapor. Sensors on the weather satellites are set to detect the radiation that is emitted by water vapor at specific wavelengths (6.5 to 6.9 microns). The sensors only measure the water vapor in a layer that is 6 to 10 km above the Earth's surface. Water vapor images are valuable because they display the flow patterns in this upper layer of the atmosphere. This is of interest to meteorologists because this is a region where storms tend to develop and grow.

Water vapor images also display the jet stream, which at this high altitude tend to control the movement of weather systems. The jet streams show up nicely in these water vapor images as the extended dark regions. The dark regions are areas that have little water vapor at high altitudes. The white regions are areas that have a higher level of water vapor concentration at high altitudes. Because this is an image of water vapor at high altitudes only, it is possible for a location with high amounts low-level moisture to appear dark. Generally, the very bright white regions are high clouds. Unlike other satellite images that display only the location of clouds, water vapor images can display information even in the areas that don't have cloud cover.

Notable Features

  • Water vapor images show the flow patterns in the atmosphere from 6 - 10 km
  • The shading indicates the presence of water vapor between 6 - 10 km, with darker regions indicating less water vapor at the specified altitude