AIRS

This movie shows a hidden but important ghost in the climate system: water vapor. Like other Halloween spirits, it is invisible to the naked eye. Water vapor frequently condenses into familiar --and visible-- clouds and rain. Water vapor is also the most significant greenhouse gas in the atmosphere, about twice as important as the more familiar carbon dioxide. This ghost of the atmosphere is seen every day, not just Halloween.

The floating spirit in this movie shows the height of a constant value of water vapor as it varies over the summer and fall of 2005. This water vapor surface is highest in the tropics where vapor amounts are largest. The greatest heights (about 3.2 km or 2 miles) occur over south Asia where monsoon thunderstorms carry water vapor high into the atmosphere. Other thunderstorms over Africa and South America lift water vapor there. In some regions of the tropics --such as off the west coast of South America-- the height of the surface is lower. This indicates drier air brought downward to the surface in these regions. The ghost's waving arms over the northern hemisphere show tendrils of water vapor being pulled from tropical storms into higher latitudes. Some of this water vapor may condense as rain or snow, making for a dark, scary Halloween for trick-or-treaters far from the warm tropics.

Credit: Vince Realmuto and Charles Thompson, AIRS Data Visualization Team, Jet Propulsion Laboratory