ABSTRACT
Weather data come chiefly from weather observing stations on land, and from ships at sea. Weather forecasting requires information on winds and temperature aloft; so wind, temperature and humidity profiles are measured daily at about a thousand weather stations. Measurements are also taken at climate stations, where instruments indicate the daily extreme temperatures, twice-daily humidity, daily rainfall and, in some cases, hours of sunshine, soil temperatures, pan evaporation and dew. Forecasters compress the information from a weather station by means of an internationally agreed code, which allows data to be sent rapidly by cable or radio, and shared with other weather bureaux. A statistical forecast uses past records of relevant factors at a place to find equations relating them to the weather on the following day, and then uses the equations for forecasting.
