Why does stevenson screen have louvered side?

The louvered sides of a Stevenson screen allow for proper ventilation while protecting the instruments inside from direct sunlight and precipitation. This design ensures that air can flow freely, helping to maintain accurate temperature and humidity readings. The louvres also minimize the impact of external factors, such as wind and radiation, leading to more reliable meteorological data collection. Overall, the louvered structure is essential for creating a controlled environment for weather instruments.