While the popular image of the Battle of Britain is of permanently fine, hazy skies criss-crossed with contrails, the summer of 1940 actually saw mixed weather. September 15, known as Battle of Britain Day because of the heavy raids, had 50% cumulus cloud cover, the lightest for over a week.
Cloud cover mattered because of the difficulty of navigating without visual landmarks. The German Knickebein radio location system was not yet widely used. Pilots had to rely on dead reckoning, calculating position from speed and bearing as sailors had for centuries. Unlike sailors though, pilots only knew their speed relative to the air, so they also needed an accurate estimate of the wind speed and direction.
Specialist Luftwaffe squadrons known as Wettererkundungsstaffel flew weather reconnaissance missions over Britain to establish the wind conditions and cloud cover. Their daily reports determined when, whether and where it would be possible to launch bombing raids. After 15 September the weather worsened making attacks more difficult.
Weather was also important for the defenders. The RAF established meteorological offices at each group headquarters, with a network of weather stations in the surrounding area. These stations took readings and launched balloons at intervals to measure wind speed at different altitudes, receiving vital assistance from the civilian Met Office.
The Battle of Britain was won by the Few, but they could only fly with the support of unseen legions toiling in backrooms over weather forecasts.
.png?w=600)
