But there are more subtle clues, too. Increasing cirriform clouds overhead, especially if they evolve into thickening and lowering cloud layers, indicates air being lifted, often in advance of an approaching front. And increasing vertical development in cumulus clouds can indicate an increasing probability of storms. Conversely, if cumulus clouds become ragged at the edges and show no sharp-edged dome-shaped structures, the likelihood of imminent storms or precipitation is reduced.
There are many more examples given in popular books on weather that point out relationships between clouds, their properties and weather systems. Sign up for our email newsletter. Already a subscriber? Sign in. Thanks for reading Scientific American. Create your free account or Sign in to continue. See Subscription Options. Discover World-Changing Science.
Donald H. Lenschow, a senior scientist at the National Center for Atmospheric Research, offers the following explanation: Clouds form whenever and wherever there is more water in a particular volume of the atmosphere than it can hold as vapor. Get smart. Sign Up. Support science journalism. Great course 27 Jun, Learn About Weather 25 Jun, Great cpurse 23 Jun, Clouds form when the invisible water vapour in the air condenses into visible water droplets or ice crystals.
There is water around us all the time in the form of tiny gas particles, also known as water vapour. There are also tiny particles floating around in the air — such as salt and dust — these are called aerosols.
Aerosols make it easier for the water vapour to condense, and once the process starts, eventually bigger water droplets form around the aerosol particles, and these water droplets start to merge with other droplets, forming clouds. Want to keep learning? This content is taken from University of Exeter online course. See other articles from this course. This article is from the online course:. News categories.
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Register for free. FutureLearn offers courses in many different subjects such as. That warmed air starts to rise because, when warm, it is lighter and less dense than the air around it.
As it rises, its pressure and temperature drop causing water vapor to condense. Eventually, enough moisture will condense out of the air to form a cloud. Several types of clouds form in this way including cumulus, cumulonimbus, mammatus, and stratocumulus clouds.
Some clouds, such as lenticular and stratus clouds, form when wind blows into the side of a mountain range or other terrain and is forced upward, higher in the atmosphere. The side of the mountains that the wind blows towards is called the windward side. The side of the mountains where the wind blows away is called the leeward side. This can also happen without a dramatic mountain range, just when air travels over land that slopes upward and is forced to rise.
The air cools as it rises, and eventually clouds form. Other types of clouds, such as cumulus clouds, form above mountains too as air is warmed at the ground and rises.
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