Observations about the temperature, rainfall, sunshine and cloudiness, direction and velocity of winds, etc., being taken at fixed hours are transmitted by code to the forecasting stations by the meteorological observatories. Data is also collected on ships plying on the Indian seas, weather observatories in Antarctica, the International Indian Ocean Expedition, and the launching of rockets and weather satellites. The central office keeps a record of the observations, which forms the basis for making a weather map. The atmospheric observations which are procured from hill stations, aeroplanes, pilot balloons, etc., are plotted separately. Meteorological observatories transmit the data to the Central Observatory at Pune twice a day.
The data received from various weather observatories cannot be incorporated in one single chart. Therefore the meteorological symbols are used. Weather charts provide the primary tools for weather forecasting.
They help in locating and identifying different air masses, pressure systems, fronts and areas of
Precipitation. Weather forecasts help in taking safety measures in advance in case of the likelihood of bad weather, i.e., cyclone and thunderstorm, etc. Predicting weather a few days in advance may prove very useful to farmers and ship's crew, industrialist, traders, pilots, fishermen, defence forces, etc.