Weather forecasting is the application of science and technology to predict the state of the atmosphere for a given location. Weather forecasting involve the prediction of the state of the atmosphere in a particular region over a period 24 to 48 hours. It is very difficult to predict the weather for more than two weeks because weather changes without warning.
Weathermen collect data on weather and then provide weather predictions for a certain period of time. For this to be achieved, weather stations are distributed in different parts of a given country or region. The data collected from the various weather stations is examined and synoptic charts are produced. A synoptic chart is a special chart drawn by experts in weather stations for reporting and indicating weather conditions in various parts of a country or region.
Elements of weather that are observed in order to predict the expected weather conditions over a place include: wind direction, atmospheric pressure, rainfall, temperature and cloud cover. In predicting weather conditions, past weather conditions are also important because they help form weather patterns which are important for forecasting.
The following are methods used in weather forecastingRADIOSONDE, This is an instrument used to register pressure and temperature from the ground to roughly 12 km above the ground. The instruments are fixed to balloons filled with helium gas and are released into the atmosphere every day at a particular time from different weather stations. The radiosonde transmits radio signals to computers on the ground station where they are analyzed. The signals transmitted give pressure, temperature and humidity readings at different altitudes. These balloons are made in such a way that they burst when they reach a certain altitude.
SATELLITES, The satellites used for predicting weather are human-made. Satellites are large electronic devices which are sent into space. They move around the earth so that they can provide various types of information. They are also used in radio, television and telephone communication. Satellites transit photographs on weather conditions on daily basis. The movement of clouds can be predicted from an analysis of the movement of winds for a period of 24 hours.
This is the simplest way of making a weather forecast. It assumes that the atmospheric conditions of a place at the time of forecast will not change. For example, if it is 28 degree Centigrade in Dodoma today, the persistence method predicts that it will still be 28 degree centigrade in Dodoma tomorrow. If two inches of rain fell in Arusha yesterday, this method predicts that two inches of rain will fall in Arusha today.
STATISTICAL FORECASTING In this method, meteorologists ask themselves: How is the weather usually like at this time of the year? They then collect records of average temperatures and rainfall over the last few years. This gives forecasters an idea of what the weather is ‘’supposed to be like’’ at a certain time of year. There are other more complex methods of forecasting weather, including the use of computers and other technologies.