Greek as­tronomer Ptolemy sim­pli­fied weather as an imag­i­nary line be­tween the equa­tor and poles


Down to Earth - - HISTORY -

quasi-global data record.

In 1872, HMSChal­lenger, a ves­sel of the Bri­tish Royal Navy, un­der­took a four-year sci­en­tific voy­age around the world, record­ing weather data ev­ery two hours through­out its jour­ney span­ning over 127,000 km. As Paul Ed­wards, his­to­rian at the Univer­sity of Michi­gan, put it in his 2010 book A Vast Ma­chine: “This was the 19th cen­tury equiv­a­lent of a weather satel­lite: an at­tempt to ob­serve the en­tire planet from a sin­gle plat­form us­ing well-cal­i­brated in­stru­ments and con­sis­tent tech­niques.”

Alexan­der Buchan, a Scot­tish me­te­o­rol­o­gist, took on the Her­culean task of clean­ing up the many in­con­sis­ten­cies in the prodi­gious Chal­lenger data. Af­ter seven years of toil­ing, he pub­lished in 1889, the re­vised data in a book

in the form of 52 beau­ti­ful colour maps of global and hemi­spheric av­er­age tem­per­a­tures, pres­sures and winds.

For most of the 19th cen­tury,how­ever,me­te­o­rol­ogy re­mained a hobby for aca­demics and dilet­tantes alike, as fore­cast­ing was a dis­tant dream yet—the science was still in its in­fancy, and hence in­ac­cu­rate. Be­sides,me­te­o­rol­o­gists didn’t have ac­cess to real-time weather data.

The ad­vent of elec­tric teleg­ra­phy in the 1850s rev­o­lu­tionised ev­ery­thing, in­clud­ing me­te­o­rol­ogy. Me­te­o­rol­o­gists could now share and an­a­lyse weather data from across the world. Even though there was lit­tle un­der­stand­ing of the com­plex physics of weather, ac­cess to global data was at least a promis­ing start­ing bench­mark to make a cal­cu­lated forecast.The US set up its first pi­lot net­work in 1949.Ten years later, the weather teleg­ra­phy net­work had over 500 weather sta­tions.

By 1900,tele­graph net­works had mush­roomed,and large parts of the world, in­clud­ing the colonies, were now con­nected by the tele­graph. This rich data set, in­stantly com­mu­ni­cated, en­abled weather of­fices to make short-range fore­casts.Even though the fore­casts were still in­ac­cu­rate, their ob­vi­ous util­ity for agri­cul­ture and ship­ping fur­ther cat­a­pulted weather teleg­ra­phy from a project run by a nexus of am­a­teurs to a vast in­fra­struc­ture spon­sored ini­tia­tive, and run by na­tion-states.

As the science of me­te­o­rol­ogy and weather sta­tions spread to other coun­tries, sci­en­tists also fer­vently pushed for global stan­dards for col­lect­ing weather data (units of mea­sure­ments,ob­serv­ing times, record­ing in­stru­ments and tech­niques) in line with sim­i­lar ef­forts in in­dus­trial man­u­fac­tur­ing. How­ever, me­te­o­rol­o­gists would have to wait (for var­i­ous rea­sons, in­clud­ing the two World Wars and the en­su­ing Cold War) an­other 75 years for this­come about.

Me­te­o­rol­ogy’s next big mo­ment came with the two World Wars.War­ring armies soon re­alised that weather fore­cast­ing could be used as strate­gic weapon, es­pe­cially with the ad­vent of air war­fare. Around the same time, physi­cists study­ing the at­mos­phere con­cluded that mea­sure­ments of the up­per lay­ers of the at­mos­phere were as im­por­tant as sur­face ones to the fast evolv­ing tech­niques of nu­mer­i­cal weather pre­dic­tion. Thus, im­pelled by this twin im­pe­tus,in ad­di­tion to the break­down of in­ter­na­tional shar­ing of weather data, na­tions be­gan in­vest­ing heav­ily in the growth of dense ob­serv­ing net­works and up­per-air mea­sure­ments by air­crafts. This was con­tin­ued dur­ing World War II, helped this time by new tech­nolo­gies such as more so­phis­ti­cated air­craft, ra­dios, air bal­loons, and fi­nally com­put­ers.

With this mam­moth ex­pan­sion of weather data, the stage was set for the next revo­lu­tion in me­te­o­rol­ogy—nu­mer­i­cal weather pre­dic­tion (nwp).By the late 1940s,the world was cre­at­ing far more weather in­ter­pre­ta­tions than could be gain­fully used by ei­ther fore­cast­ers or cli­ma­tol­o­gists.Yet by the late 1950s,as nwp mod­els be­came more so­phis­ti­cated and en­com­pass­ing, it be­came clear that the avail­able data was not enough—at least, not in the right for­mat, from the right places,and at the right times.

This dire need,which was cru­cial for the suc­cess of nwp, even­tu­ally led to the cre­ation of the World Weather Watch (www) un­der the aus­pices of the World Me­te­o­ro­log­i­cal Or­ga­ni­za­tion (wmo) in 1963. www is a vast plan­e­tary net­work to col­lect 365x24x7 weather in­for­ma­tion—from ground weather sta­tions, ships, air­planes, radars, and satel­lites.This data, freely avail­able to any­one in­ter­ested in weather,is not sim­ply col­lected; it is, in the tra­di­tion of Buchan, ver­i­fied, fil­tered, in­ter­preted and fi­nally in­te­grated by com­puter mod­els.

The 19th cen­tury Bri­tish art critic and poly­math John Ruskin’s had dreamt of a “per­fect sys­tem of me­thod­i­cal and si­mul­ta­ne­ous ob­ser­va­tions”.www is the cul­mi­na­tion of that dream.

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