Signal Summer 2019 Newsletter

www.alliancecom.net 5 A Brief History of Modern Weather Forecasting W hile people have attempted to predict the weather for millennia, modern forecasting didn’t begin until the 19th century. The invention of the electric telegraph allowed forecasters to quickly get information about conditions upwind, making it possible to know what was coming their way. Manual and Computer Prediction Two British men, Francis Beaufort and Robert FitzRoy, are credited with establishing weather forecasting as an actual science. Beaufort developed the Wind Force Scale, which numeri- cally describes the severity of storms. FitzRoy established prediction charts and land stations that would telegraph weather conditions to him, enabling him to develop daily weather forecasts. In the early 20th century, advances in atmospheric physics led to the development of numerical prediction, which uses mathematical models to predict weather. This method required so many calculations that it wasn’t until the 1950s, when computers became available, that the method was put to regular use. The first computerized weather forecast was performed by an American team of meteorologists. Published Forecasts Weather forecasts began to be published in The Times of London in 1861. In the U.S., weather forecasts were initially made over the radio in 1925. The first televised forecasts were broadcast by the British Broadcasting Corporation (BBC) in 1936 and in the U.S. in the 1940s. TV weather forecasts with on-screen weather satellite information and computer graphics began in the late 1970s. Now, of course, weather forecasts are as easy to get as a few simple taps on your computer or phone. For a more detailed look at the history of weather forecasting, check out the time line at timemapper.okfnlabs.org/manunicast/history-of-weather-forecasting#0. Behind the Scenes With Green Screens When you watch weather reports on TV, you typically see the weather person standing in front of an image that shows temperatures, weather graphics, and storm movement. You’re probably aware that all of this weather magic is done using a tech- nology called green screen, which is also used in movie development. But exactly how does a green screen (also known as a chroma key) work? It starts with a green fabric or paint background. The image—which can be a static photo, a video, or any other graphic— is projected onto the screen by a computer connected to the TV camera. The computer has instructions to project onto anything green, so that’s why the image doesn’t show up on the person (unless they’re wearing something green). Because the weather person is still seeing just a green screen, they must look at a nearby monitor to know where to point when showing you an approaching storm or temperatures in a certain city. FAST FACT: Lightning often follows a volcanic eruption.