HYDERABAD: In a small laboratory at IIT-Hyderabad, raindrops are suspended mid-air as Prof Kirti Chandra Sahu and his team study how they change in size, shape and temperature — an effort that has now earned him the National Awards to Teachers 2026.
A raindrop may seem simple as it falls from the sky, but its journey from cloud to ground involves complex changes. For Prof Sahu, a founding faculty member of IIT-H’s Department of Chemical Engineering, understanding those changes has been the focus of years of research. He received the National Awards to Teachers 2026 (NAT 2026) on Saturday, on the occasion of Teachers’ Day, for his academic and research contributions, including pioneering studies on raindrop shape and size distribution at different altitudes. The research could help improve rainfall prediction.
His fascination with raindrops eventually led to the creation of a unique raindrop research facility at IIT-H. Conceived around 2013, the facility took nearly a decade to establish.
Bringing the sky into the lab
Speaking to TNIE, Prof Sahu says that raindrops do not remain unchanged as they descend. They pass through atmospheric layers with varying temperature and humidity,causing them to change dynamically. Studying these changes at different altitudes would normally require observations across several kilometres of atmosphere,which is difficult to replicate experimentally.
The facility addresses this by suspending raindrops in mid-air using upward air currents while controlling the surrounding atmospheric conditions. By varying temperature and humidity, researchers can recreate conditions similar to those encountered by raindrops as they travel from clouds to the ground.
The objective is to understand raindrop size distribution under different atmospheric conditions,an important parameter used by weather radars. Better information on raindrop characteristics can improve rainfall estimates and has wider applications in climate-change modelling, water-resource management and the study of extreme weather events such as cloudbursts.
The research has also been tested against observations from the Government of India’s HYPEx project, which used research aircraft equipped with multiple sensors to measure rainfall. Sahu’s team compared its results with observations from Bhubaneswar, Vijayawada and Hyderabad.
Rural roots, global education
Sahu’s association with IIT-H dates back to 2009, when the institute was still in its formative years and functioning from a school building at the Ordnance Factory. As a founding faculty member, his responsibilities extended beyond teaching. Developing infrastructure, creating curricula, taking on academic leadership roles and pursuing research had to happen simultaneously.
“It was challenging, but somehow I could manage to do both simultaneously,” he recalls.
Over the years, he has seen the institute evolve into one of the country’s prominent institutions of higher education, while his own research ambitions also took shape.
His journey began in Korua, a small village in western Odisha. After completing his schooling there, he moved to the University College of Engineering, Burla, to pursue a BTech in Mechanical Engineering. He later completed his master’s and PhD at the Jawaharlal Nehru Centre for Advanced Scientific Research in Bengaluru in about five years, followed by a postdoctoral stint at Imperial College London before returning to India and joining IIT-H.
Growing up in a rural setting with limited resources, access to books and awareness of educational opportunities were sometimes major hurdles. He said his master’s and PhD years proved to be a turning point, when he became clear about his goals.
What began as an inclination towards becoming a scientist eventually developed into a career combining research and teaching. For him, research itself is a form of teaching, particularly in higher education, where postgraduate and doctoral students learn through active participation in research.
‘More responsibility, not an endpoint’
The NAT 2026 recognition has given Sahu a sense of fulfilment, but he sees it less as an endpoint and more as encouragement to do more. “I feel extremely happy and fulfilled, but at the same time, I feel more responsible. The day we become stagnant, that is the end of our life,” he says.
Prof Sahu believes that every generation should strive to make the next one more knowledgeable, capable and advanced.