Part I Four Centuries Of Surprises

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A technical breakthrough came with the invention and perfection of the vacuum tube, so that wireless communication could be established between the balloon-borne instruments and the weather observer on the ground. During the 1930s small packages containing lightweight instruments and radio transmitters, which could be carried aloft by balloons, were perfected and produced on a mass scale. By 1940 a number of upper-air sounding stations were in operation along the airways, sending twicedaily flights of radiosondes, as the combined package was called, to measure temperature, humidity, and pressure conditions aloft. The third dimension of the atmosphere had been conquered.

The weather observer’s ability to actually see beyond the horizon became a reality in the 1940s with the perfection of radar. Practical radars were originally developed from efforts to track lightning discharges by electrical triangulation, and by 1940 it was known that raindrops would reflect radar beams, meaning that it was possible to see falling precipitation and storm formations at a distance of about two hundred and fifty miles beyond the horizon. The uses of radar have increased steadily, and today the Doppler radar makes possible the detection of wind shear and turbulent downbursts so dangerous to landing aircraft.

Despite the enormous growth in the number of weather stations and the expansion of communication facilities, observations of surface weather conditions in 1960 were available from only about one-fifth of the world’s land and water surfaces. The uncovered areas lay mostly over the oceans, where tropical storms went undetected until they neared land or crossed a shipping lane. The development of rocketry after World War Il and the improvements in television and transitors enabled a “seeing-eye” camera to be carried aloft and launched into orbit, and the first successful weather satellite went to work on April 1, 1960. The TIROS series (Television Infrared Observation Satellite) was followed by much more sophisticated space vehicles. Placed over the equator in stationary orbit, these probes provide almost complete global coverage of existing weather conditions. Now the weather observer can literally see around the world.

Other technologies have also extended our reach. SODAR (Sound Detection and Ranging) is a sounding technique employed to measure cloud heights, temperature variations at various levels, and wind movement in the lower atmosphere. LIDAR (Light Detection and Ranging) utilizes laser beams to gauge visibility and cloud height from automatic weather stations placed in remote areas on land and sea. But the most important technical breakthrough for weather forecasting came with the development of the electronic computer, which can produce a prediction by receiving a mathematical model of a current weather pattern and projecting it into the future.

Meteorologists can now boast that their predictions are on target about 80 percent of the time. Their performance should improve even further as we draw closer to a full understanding of the vast atmosphere that makes life possible on our planet. But no conceivable future will spare us the caprices and buffetings that the first settlers complained about in their letters home.