Last weekend, I attended a (free) SKYWARN training class in my area, and have become a trained severe weather spotter [NOT a storm chaser!].* In the class, we covered topics such such as safety around storms, storm development, and identification of cloud formations indicative of severe or intensifying storms.
Despite the many advances in technology—from geosynchronous weather satellites to dual-polarization radar to networked automated weather stations across the country—there are times when there is little substitute for human eyes.
Humans are very good at pattern recognition, and with a little training can identify different types of clouds, rocks, or observe that a valley was carved by a glacier. You might want to go outside sometime and take a close look at something, be it a cloud, tree, rock, or animal. What do you notice about it?
I’ll describe a few of the things I notice in the photograph above. There’s a low, dark cloud base, and toward the center-left are some disorganized clouds beneath the base. Rain is visible along the left side beyond the hill. A stiff breeze is blowing directly toward the camera, as indicated by the wavelets on the water.
With those observations in mind, I would interpret the scene in this way: a cold front is passing through, and these clouds are part of a squall line. The front has nearly reached the photographer’s location. Warm, humid air toward the right is buoyantly rising over the colder air. As it cools upon rising, the water vapor condenses and precipitates as rain. While it’s not clear from this photograph, the low-level clouds may be part of a shelf cloud, or there may be a shelf cloud above the frame of the picture. The primary hazards here would be high winds, lightning, heavy rain, and possibly some hail.
Some people I’ve talked with have suggested that when taking notes and observations in the field, that the left-hand pages of the notebook should be used for observations, and the right-hand pages for interpretation. Keeping descriptions and interpretations distinct can help when an alternate interpretation is brought up, or when writing a paper with separate results and discussion sections. The results are strictly the measurements and observations, and the discussion then describes the interpretation off them.
* If you live in the US and are interested in severe weather, you should check with your local weather office to see when and where they offer training.**
** Some places, such as the San Francisco Bay Area, don’t really have weather, so classes are few and far between. For more excitement in your meteorology, you should go to the Midwest. You could also take the online course (not necessarily accredited in your area).