Topographic Control of Temperature Distribution and Thermal Comfort: A Comparative Study of Hill and Plain Stations in North-East India

Abstract

This study investigates the role of topography in controlling temperature distribution and thermal comfort across selected hill (Shillong, Aizawl and Kohima) and plain (Guwahati, Silchar and Agartala) stations in North-East India using Indian Meteorological Department (IMD) climatological normal data for the period 1991–2020.The analysis incorporates key thermal parameters, including mean maximum and minimum temperature, wet bulb and dry bulb temperature, and derived indices such as diurnal temperature range (DTR) and Discomfort Index (DI).The results reveal a clear altitudinal variation in temperature, with hill stations such as Shillong, Aizawl, and Kohima recording lower temperature ranges (maximum: 15.2°C–28.8°C; minimum: 5.1°C–20.2°C), while plain stations such as Guwahati, Silchar, and Agartala exhibit significantly higher values (maximum: 23.9°C–33.3°C; minimum: 10.8°C–25.9°C). A statistically significant inverse relationship between elevation and temperature is observed (p < 0.05), supported by correlation and regression analysis. The diurnal temperature range (DTR) varies from 14.7°C to 17.1°C across the study area, with lower values observed in hill stations and relatively higher values in plains, indicating greater thermal variability in lowland regions. Thermal comfort analysis based on the Discomfort Index (DI) shows that hill stations remain within the comfortable to slightly uncomfortable range (DI < 24°C), whereas plain stations frequently experience moderate to severe discomfort, with DI values reaching up to ~29°C during the monsoon season. Furthermore, higher wet bulb temperatures and smaller dry–wet bulb differences in plain regions indicate increased atmospheric moisture and humidity-induced discomfort. The findings highlight the dominant role of topography in shaping regional thermal regimes and emphasize the importance of elevation in influencing temperature variability and human thermal comfort. These insights are crucial for climate assessment, environmental planning, and sustainable regional development in North-East India.