The effects of the weather on aviation

Except perhaps for local or very short flights, a pilot, before taking off, obtains a weather forecast (1) giving him the weather conditions which are expected along the route of his flight and at his destination. Because weather conditions affect aircraft in flight, to a considerable extent, special aviation forecasts are provided by meteorologists (2) at weather offices all over the world.

The meteorologist, or forecaster, prepares a weather chart which shows the current weather conditions (3) over the whole country. The current weather chart is called a synoptic chart. (4) This synoptic chart shows the areas of low pressure, (5) the areas of high pressure, (6) where precipitation (7) is falling, and all other weather conditions across the country.

From this weather map, the forecaster can advise pilots of the weather conditions they can expect to encounter during their flights. A high pressure area, for instance usually means good weather while a low pressure area usually involves one or more fronts (8) producing clouds and precipitation over many hundreds of miles.

A pilot needs to know the wind direction and speed. A headwind (9) will obviously delay the arrival of flights and is to be avoided if at all possible. A tailwind (10) on the other hand, can be of great advantage as it increases the ground speed (11) and results in a reduction in fuel consumption. Winds vary with altitude, and also from one place to another, so information on winds is very important.

Pilots will pay particular attention to a low which lies en route, and the weather conditions associated with that low pressure area. The associated cold (12) or warm fronts (13) could involve clouds, thunderstorm, snow, rain, and turbulence. From his charts, the meteorologist can forecast where this weather will be at a certain time in the future, and with the help of these predictions, the pilot will decide which route to fly and when and he will know what weather conditions to expect. Should the forecast be very bad, for example, dense fog or poor visibility due to snow, the pilot may decide to postpone his flight. A pilot flying VFR would also cancel his flight because of low ceiling (14) or low overcast (15) conditions en route.