http://www.airspacemag.com/military-aviation/Prairie-Wind.html

Changes in wind and air pressure in the first mile of atmosphere
could also have a detrimental effect on the performance of new jets the Air
Force was testing. To understand how air near the ground behaved—how it
circulated, how it warmed and cooled—the Air Force was taking temperature and
barometric readings every few hours at base runways. Lettau was called in to
figure things out. If successful, his experiment would give the Air Force
standards it could follow without continually having to take runway readings.