Weather from Above

Though the U.S. weather satellite Tiros I still circles the earth every 99 minutes, it is electronically dead. Yet during its active life of 78 days, Tiros I transmitted 22,952 cloud-cover pictures that still keep meteorologists in a state of round-eyed euphoria. Never before had earthmen seen so sweeping a view of their planet's splotchy atmosphere.

Last week Meteorologist David Johnson of the U.S. Weather Bureau told how Tiros' twin TV cameras, riding 400 miles up, saw things no one had noticed before--and gave a new dimension to the not-so-precise science of meteorology. Until Tiros, the story of what happens overhead had been a matter of educated guesswork, a smattering of facts well-larded with interpolation. Only a few areas (Europe, parts of the U.S., Japan) have tight networks of weather observation posts, and even these can only monitor a relatively small patch of weather. A ground observer can see cloud effects about five miles away. If he has radar, he can report heavy rain at a somewhat greater distance; even aircraft at 45,000 ft. can see only 150 miles. Between the observers are wide-open spaces big enough to hold whole strings of tornadoes. Some 80% of the earth's surface has no reporting stations at all. In many unfrequented parts of the ocean, a hurricane can be born and grow to adulthood in perfect privacy.

Patterns & Shapes. During its electronic lifetime, Tiros I photographed away much of the atmosphere's privacy. On May 19, for instance, the camera pictured a bright, square cloud in an isolated position about 50 miles northwest of Wichita Falls, Texas (see cut). Weathermen had no previous reports of such a formation. They looked up the records and found that this peculiar cloud had moved northeastward and raked Oklahoma with four tornadoes. When future weather satellites take to space, one mission will be to watch for clouds of this sort and warn against them before they start doing damage.

The Air Force's Air Weather Service considers even relatively harmless clouds important because they may hamper military operations. Aside from the obvious need to know the weather over potential targets, the airmen would like a precise picture of the weather en route in all missions. The aerial refueling of bombers requires clear, smooth air, and the all-seeing eyes of Tiros can tell bombers and tankers where to make their rendezvous.

Clouds also show by their patterns and shapes what motions of atmosphere are stirring up the weather. Tiros I took pictures of spiraling cloud systems reaching from Alaska to Southern California. Over Argentina, it showed clouds that traced the location of the high-altitude jet stream of the Southern Hemisphere. Meteorologists were surprised to learn from Tiros I that great, swirling cyclonic systems thousands of miles apart are sometimes connected by filaments of cloud.

Neph Analysis. The operational successors of Tiros I will probably revive a 19th century method of weather prediction called "neph analysis" (nephos--Greek for cloud). Weathermen in Antarctica will welcome satellite cloud pictures to tell them whether it is safe for a supply plane to start from New Zealand. The Indian Ocean, where few ships or airplanes pass, will be watched by neph analysis for juvenile typhoons.

When the next weather satellite, Tiros II, is launched next fall, it will have eight infra-red sensors of two types to give some idea of the temperature of the earth, ocean or clouds below. This is important for weather forecasting because heat from the sun is the prime mover that makes the atmosphere circulate. Other likely improvements are a better TV camera with sharper focus and a system to stabilize the satellite so that the camera is always looking at the earth below.

Operational weather satellites, to be called Nimbus, are not to be expected for several years. There will have to be at least two of them, perhaps as many as six, circling on polar orbits at the same time. To do a good job on the earth's weather they will have to send their worldwide pictures simultaneously, not just as they pass reporting stations, and in such a way that their information can be fed into the computers that the Weather Bureau uses to forecast the weather. All this will take a great deal of planning, testing and money, but everybody concerned--the Weather Bureau, Pentagon, and National Aeronautics and Space Administration--is convinced that the triumphs of Tiros I have made it worthwhile.

This file is automatically generated by a robot program, so reader's discretion is required.