Cirrocumulus Mid-Level Clouds
Altocumulus Low-Level Clouds
Stratocumulus Clouds with Vertical Development
The weather page is prepared by Daniel Bezte. Dan has a BA Honours degree in geography, specializing in climatology, from the U of W. He has taught climate and weather classes at the U of W, and is a guest climate expert on CJOB’s morning show with Larry Updike. Daniel runs a computerized weather station on his 10 acres near Birds Hill Park, which he plans to develop into a small vegetable and fruit hobby farm.
Daniel welcomes questions and comments at [email protected]
Where would we be without clouds? Besides being esthetically pleasing to look at (if you’re not having to look at them all the time), without them there would be no rain or snow, thunder and lightning, or rainbows. If we were to define a cloud we could say that it is a visible collection or aggregate of tiny water droplets or ice crystals floating or suspended in the air. Stealing a line from Meteorology Today, “some clouds are found only at high elevations, while others nearly touch the ground. Clouds can be thick or thin, big or little – they exist in a seemingly endless variety.” Identifying all the different types of clouds can be a little tough, but with some practice you can become reasonably proficient at identifying them.
Our current method of naming and classifying clouds was developed in 1803 by Luke Howard, an English naturalist. His system employed the use of Latin words to describe the clouds as they appear from the ground. Clouds that appeared to look like sheets were called stratus, the Latin for layer. Puffy clouds were called cumulus, the Latin for heap. Wispy clouds were called cirrus, the Latin for curl of hair, and finally, rain clouds were called nimbus, meaning violent rain, in Latin. So in essence, Howard’s system had four different cloud types. These types could then be combined to cover other types of clouds. For example, stratus clouds that have rain falling from them would be called nimbostratus; cirrus clouds that form a layer would be called cirrostratus and so on.
In 1887, Abercromby and Hildebrandsson expanded Howard’s system by creating four different groups in which to divide clouds. These would be high clouds, middle clouds, low clouds, and a fourth group for clouds that span more than one region – referred to as vertically developed clouds.
This is the system that we use today. Clouds are classified by the height at which they occur and then by their appearance. The following table shows the four major cloud groups and their types.
This addition to the naming and classifying of clouds does at first seem fairly simple and straightforward, but there are a couple of things that make it a little confusing. First of all, we have cloud types of stratus (layer) and cirrus (wispy). When adding in the height of the cloud we use the term cirrus for all high clouds, alto for middle-level clouds, and stratus for low-level clouds. So now they are kind of using the same word for two different things, at least for high and low clouds. When we take a closer look it does make some sense.
Wispy cirrus clouds only occur at high altitudes, so anything high up in the atmosphere will either be cirrus or have cirro attached to the front of it. Midlevel clouds are easy as we simply add the term alto to the cloud type – no double meanings here. Naming low-level clouds works like the high-level clouds, except this time we use the term stratus to describe the cloud. For example, low-level cumulus clouds would be called stratocumulus. What we don’t do is call plain cirrus clouds cirrocirrus, or stratus clouds stratostratus. This is just redundant so we simply go with the simple naming.
Next article we will continue our look at clouds and start to examine each different type of cloud and what they can tell us about our weather.