Apart from sometimes being very pretty to look at, the clouds are important components of Earth's weather and climate system - not only to observe short-term weather conditions. Clouds are active elements that play an important role in determining conditions on our planet.
From measurements on the clouds we hope to understand more about the formation and evolution of clouds, what effect they have on their surroundings and to us on Earth.
Energy balance and global warming
One important area in which clouds play a role is in the energy balance of the Earth. One important task for scientists at the moment is to find out whether clouds will warm or cool the Earth in the event of global warming. Clouds cool the Earth by reflecting sunlight back out to space but they also warm the Earth by absorbing heat radiated by the surface and thereby preventing the energy from escaping to space. The cloud type determines which effect dominates; heating or cooling.
We also need to know if there will be more clouds with global warming and whether the overall effect from more clouds will be warming or cooling. When the temperature rises the amount of vapor from the oceans will increase and we'll get more clouds that may reflect more sunlight back to space. But will more clouds cool the Earth by reflecting sunlight, or will clouds and increased water vapour trap more heat energy in the atmosphere? We don't know that yet.
Another important role for clouds involves water transport. Since clouds are made of ice or liquid water, they help redistribute water through the air, returning it to the surface as rain or snow.
In order to better predict day-to-day weather, as well as long-period trends in climate, there is much we need to learn about clouds.
15th October 2000