Met dept proposes, rain God disposes

Weather forecasting is hardly "a game of dice or something which depends on sheer luck" say experts. But despite their assertions of the serious and scientific nature of their profession, the quality of our weather reporting continues to lag behind that of the USA, Europe and other developed countries.

A meteorologist’s work is similar to mathematical modelling or astronomical prediction; they predict the atmospheric changes by observing its present state. They calculate the change over time of various inputs such as temperature, pressure, humidity, wind velocity and other parameters. By using differential equations – which can predict nearly anything given proper inputs – tomorrow’s weather is predicted on the basis of current conditions and historical precedent.

Meteorologists study the atmosphere in three dimensions, for which a large number of surface and air observations are required on a real-time basis. In addition, climate specialists maintain a network of radar stations to detect storms and cyclones, and capture cloud images beamed from satellites which can be accessed by different stations by the Meteorological Data Utilisation Centre (MDUC) in New Delhi.

In addition, data from ships on high seas are plotted in special charts called synoptic charts in which meteorologists connect all points of same pressure and draw lines, known in technical parlance as isobars. If these lines form a closed loop it indicates the formation of a low-pressure belt, which could trigger a cyclone. Cyclones are an intense vortex or a whirl in the atmosphere with strong winds that circulate anti-clockwise in the northern hemisphere, and clockwise in the southern hemisphere.

The sea-level chart, upper-air chart, and auxiliary charts give a three-dimensional picture of atmospheric conditions, which in conjunction with other types of weather reports, produce an analysis of weather patterns called a system.

Based on the behaviour of the system, intensity of wind circulation the resulting weather is measured. “Even to predict the weather for a small area we have to analyse a large area,” says a senior meteorologist, Sashidharan.

Explaining the climactic difference of India and western nations, S Kumar, Deputy Director General, Meteorological Department, says, “Many people who have a wrong impression about our department don’t realise the fact that India is a tropical country whose weather systems are very complicated and difficult to analyse. Whereas extra-tropical countries like the US, the UK and many European countries have a comparatively simple weather system – whose behavioural patterns are very easy to analyse.” He claims that the quality of tropical forecasting in India is as good as that of Japan and better than the USA . Even so, meteorologists are now attempting to go beyond the synoptic charts and adopt improved technologies for weather forecasting. “We are developing a numerical modelling technique which would make our work easier and more efficient,” Kumar adds.