Most of us  at school that warm air rises and cool air . This has always  to be a fundamental principle of science. However, a study from the University of California, Davis  that there are circumstances in which cool air rises. Researchers  that in tropical atmospheres, cold air rises because of the lightness of water vapour. Apparently, in warmer and more humid climates, water particles  more buoyant and can help cooler air rise. Lead researcher Dr Da Yang said: "Water vapour  a buoyancy effect which helps  the heat of the atmosphere to space and  the degree of warming. Without this lightness of water vapour, the climate warming would  even worse."
The scientists said humid air  lighter than dry air at the same temperatures and pressure. This is  the vapour buoyancy effect. It  cooler air containing water droplets to , which then forms clouds and thunderstorms. The resulting rain  a cooling effect in tropical areas. Another researcher, Seth Seidel, said more research is  to find out the effects rising cool air has on climate change, and on its impact on curbing the effects of global warming. Seth Seidel said: "Now that we  how the lightness of water regulates tropical climate, we  to study whether global climate models accurately  this effect." The study is  in the journal "Science Advances".