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e en route fromsingapore to sydney was flying over central australia in calm conditions when it suddenlyfell three hundred feet—enough to fling unsecured people against the ceiling。 twelve peoplewere injured； one seriously。 no one knows what causes such disruptive cells of air。
the process that moves air around in the atmosphere is the same process that drives theinternal engine of the planet； namely convection。 moist； warm air from the equatorial regionsrises until it hits the barrier of the tropopause and spreads out。 as it travels away from theequator and cools； it sinks。 when it hits bottom； some of the sinking air looks for an area oflow pressure to fill and heads back for the equator； pleting the circuit。
at the equator the convection process is generally stable and the weather predictably fair；but in temperate zones the patterns are far more seasonal； localized； and random； whichresults in an endless battle between systems of high…pressure air and low。 low…pressuresystems are created by rising air； which conveys water molecules into the sky； forming cloudsand eventually rain。 warm air can hold more moisture than cool air； which is why tropical andsummer storms tend to be the heaviest。 thus low areas tend to be associated with clouds andrain； and highs generally spell sunshine and fair weather。 when two such systems meet； itoften bees manifest in the clouds。 for instance； stratus clouds—those unlovable；featureless sprawls that give us our overcast skies—happen when moisture…bearing updraftslack the oomph to break through a level of more stable air above； and instead spread out； likesmoke hitting a ceiling。 indeed； if you watch a smoker sometime； you can get a very goodidea of how things work by watching how smoke rises from a cigarette in a still room。 atfirst； it goes straight up （this is called a laminar flow； if you need to impress anyone）； and thenit spreads out in a diffused； wavy layer。 the greatest superputer in the world； takingmeasurements in the most carefully controlled environment； cannot tell you what forms theseripplings will take； so you can imagine the difficulties that confront meteorologists when theytry to predict such motions in a spinning； windy； large…scale world。
what we do know is that because heat from the sun is unevenly distributed； differences inair pressure arise on the planet。 air can’t abide this； so it rushes around trying to equalizethings everywhere。 wind is simply the air’s way of trying to keep things in balance。 airalways flows from areas of high pressure to areas of low pressure （as you would expect； thinkof anything with air under pressure—a balloon or an air tank—and think how insistently thatpressured air wants to get someplace else）； and the greater the discrepancy in pressures thefaster the wind blows。
incidentally； wind speeds； like most things that accumulate； grow exponentially； so a windblowing at two hundred miles an hour is not simply ten times stronger than a wind blowing attwenty miles an hour； but a hundred times stronger—and hence that much more destructive。
introduce several million tons of air to this accelerator effect and the result can be exceedingly energetic。 a tropical hurricane can release in twenty…four hours as much energy as a rich；medium…sized nation like britain or france uses in a year。
the impulse of the atmosphere to seek equilibrium was first suspected by edmondhalley—the man who was everywhere—and elaborated upon in the eighteenth century by hisfellow briton george hadley； who saw that rising and falling columns of air tended toproduce “cells” （known ever since as “hadley cells”）。 though a lawyer by profession； hadleyhad a keen interest in the weather （he was； after all； english） and also suggested a linkbetween his cells； the earth’s spin； and the apparent deflections of air that give us our tradewinds。 however； it was an engineering professor at the école polytechnique in paris；gustave…gaspard de coriolis； who worked out the details of these interactions in 1835； andthus we call it the coriolis effect。 （coriolis’s other distinction at the school was to introducewatercoolers； which are still known there as corios； apparently。） the earth revolves at a brisk1；041 miles an hour at the equator； though as you move toward the poles the rate slopes offconsiderably； to about 600 miles an hour in london or paris； for instance。 the reason for thisis self…evident when you think about it。 if you are on the equator the spinning earth has tocarry you quite a distance—about 40；000 kilometers—to get you back to the same spot。 if youstand beside the north pole； however； you may need travel only a few feet to plete arevolution； yet in both cases it takes twenty…four hours to get you back to where you began。
therefore； it follows that the closer you get to the equator the faster you must be spinning。
the coriolis effect explains why anything moving through the air in a straight line laterallyto the earth’s spin will； given enough distance； seem to curve to the right in the northernhemisphere and to the left in the southern as the earth revolves beneath it。 the standard wayto envision this is to imagine yourself at the center of a large carousel and tossing a ball tosomeone positioned on the edge。 by the time the ball gets to the perimeter； the target personhas moved on and the ball passes behind him。 from his perspective； it looks as if it has curvedaway from him。 that is the coriolis effect； and it is what gives weather systems their curl andsends hurricanes spinning off like tops。 the coriolis effect is also why naval guns firingartillery shells have to adjust to left or right； a shell fired fifteen miles would otherwisedeviate by about a hundred yards and plop harmlessly into the sea。
considering the practical and psychological importance of the weather to nearly everyone；it’s surprising that meteorology didn’t really get going as a science until shortly before theturn of the nineteenth century （though the term meteorology itself had been around since1626； when it was coined by a t。 granger in a book of logic）。
part of the problem was that successful meteorology requires the precise measurement oftemperatures； and thermometers for a long time proved more difficult to make than you mightexpect。 an accurate reading was dependent on getting a very even bore in a glass tube； andthat wasn’t easy to do。 the first person to crack the problem was daniel gabriel fahrenheit； adutch maker of instruments； who produced an accurate thermometer in 1717。 however； forreasons unknown he calibrated the instrument in a way that put freezing at 32 degrees andboiling at 212 degrees。 from the outset this numeric eccentricity bothered some people； and in1742 anders celsius； a swedish astronomer； came up with a peting scale。 in proof of theproposition that inventors seldom get matters entirely right； celsius made boiling point zeroand freezing point 100 on his scale； but that was soon reversed。
the person most frequently identified as the father of modern meteorology was an englishpharmacist named luke howard； who came to prominence at the beginning of the nineteenthcentury。 howard is chiefly remembered now for giving cloud types their na