Even in an era of advanced satellites, radar systems and sophisticated computer models, the radiosonde attached to weather balloons continues to play a crucial role in weather forecasting. The India Meteorological Department (IMD) has been launching hydrogen-filled weather balloons with radiosondes from its Thiruvananthapuram centre twice daily since 1956.

According to Neetha K. Gopal, Director of IMD, Thiruvananthapuram, one of the most accurate methods for studying the atmosphere is the use of a radiosonde attached to a weather balloons. Attached to weather balloons, the instruments collect data on temperature, humidity and wind conditions at different altitudes, enabling meteorologists to create a vertical profile of the atmosphere.

Ms. Gopal said that though weather balloons may appear to be older technology, the instruments attached to them are modern and highly efficient. The software they use today has undergone significant technological improvements over time. The sensors and GPS-based tracking systems together provide crucial information about the atmosphere. Data from the radiosonde is received every second as the balloon ascends through the atmosphere.

The general altitude of a weather balloon before bursting is 30 km. Ms. Gopal stressed the fact that there is currently no alternative technology that can completely replace radiosondes. Technologies such as vertical profilers are being introduced in different parts of the country. However, radiosondes continue to be used as a standard method for validating data collected by observation systems, including satellites and radars.

Twice a day, at 5:30 am and 5:30 pm, the IMD launches weather balloons. Regular monitoring becomes especially important during the monsoon season, as the data helps scientists study wind patterns and understand the vertical structure of the atmosphere, contributing to more accurate weather forecasts.

Most practical

Hydrogen is used to fill the balloons because it is the most practical and safest gas for routine observations. While helium can be used, it is generally reserved for operations requiring greater altitudes rather than daily launches. Each launch is carried out by two trained personnel. Once released, the radiosonde cannot be recovered or reused, making the exercise a recurring operational expense.

The Director also highlighted the importance of weather observations for aviation, agriculture, irrigation and disaster management. She also stated that weather observation and forecasting depend not only on surface observations but also on conditions at upper levels of the atmosphere. To raise public awareness of IMD’s activities, the centre occasionally conducts outreach programmes and open-house events. Students and the public are invited to observe the launch and learn more about weather forecasting.

The author, Malavika Devi J.R., is an intern at The Hindu, Thiruvananthapuram