Whatever the weather, the barometers and weathermen usually manage to get it wrong. So how can we predict with accuracy, asks Jerry Wellington.
Understanding Weather: Precipitation; Storms; Why weather changes; Winds Each 13-min video Pounds 26.50 plus VAT and pp. Viewtech Film and Video, 161 Winchester Road, Brislington, Bristol BS4 3NJ.
Most people would like to understand the weather and why it changes, even if the chaos theorists tell us that perfect prediction is impossible. This series of four videos will certainly help to explain why we have winds, storms, rain, hail and snow without pretending that we can forecast with any long-term certainty when they will arrive.
The series features a very American but very likeable animated character called Wesley who knows nothing about weather but wishes to join the meteorologists' version of the FBI the WBI. Wesley's training for the Weather Bureau of Investigation is the theme of the four videos as he learns to use a variety of instruments including a thermometer, weather vane and barometer.
Probably the most eye-catching video is Storms, which explains how hurricanes, tornadoes and thunder storms start, how they work (as far as we know) and what effects they have.
Some of the film is quite dramatic, and the explanations are kept fairly simple, so in my view this video would form the best starting point for the series. After the 13 minutes, Wesley sums up what he has learnt in his training for the WBI. This is a useful teaching strategy and works well on each of the titles.
Precipitation is a slightly more involved topic but again is explained clearly and simply with the help of some excellent film, sometimes speeded up. The viewer should by now be used to the American approach and Wesley's high-pitched accent and be able to cope with the explanations of evaporation, condensation, dew, rain, snow, fog and cloud covered in this title. Footage of a glider rising on thermals helps to explain convection and the video also remembers to stress the importance of dust particles in the formation of clouds.
Winds makes an unusual start in the downtown streets of an American city by showing the varying directions that city wind takes, compared with the more constant directions of ocean winds such as the Westerlies. The video talks about the jet stream high above the clouds, its amazing speed (up to 250mph) and its great importance to aircraft. The importance of temperature differences in causing wind is well explained, starting with a toy windmill held above a household oven and going on to show the main wind patterns in both hemispheres and the two poles.
Finally, the most difficult video (which I would leave until last) covers Why the Weather Changes. This begins with the concept of "air masses" and talks of polar air masses moving south and tropical masses moving north what happens when these masses meet is the subject of most of the 13 minutes, as young Wesley watches a weather front approaching. He uses a barometer, a thermometer, and a weather vane to show the wind getting stronger and the barometer falling. This video covers some difficult ideas and terminology in a short space of time and moves along at quite a pace, so it will need reinforcing and perhaps a second showing. Again, though, Wesley sums up at the end and reminds us what we should have learnt quite a lot in 13 minutes.
Each of the videos is also supported by a small sheet outlining the content, setting out the objectives and giving a list of questions which the attentive viewer should be able to answer at the end. As a package these four titles and supporting sheets will cover most of the content on weather for students up to key stage 4 in both the science and geography syllabuses.