The Stevenson screen is a weatherproof enclosure used to house thermometers and other meteorological instruments. It is designed to protect the instruments from the effects of the sun, rain, and wind, and to ensure that they are exposed to a free flow of air.
The slatted sides of the Stevenson screen allow air to circulate freely around the instruments, which helps to keep them at a constant temperature. This is important because even small changes in temperature can affect the accuracy of the readings. The slats also help to block out direct sunlight, which can cause the instruments to heat up and give false readings.
In addition to the slatted sides, the Stevenson screen also has a double roof that helps to insulate the instruments from the heat of the sun. The screen is also painted white to reflect sunlight and further reduce the risk of overheating.
By controlling the temperature and air flow around the instruments, the Stevenson screen helps to ensure that they provide accurate and reliable readings. This is essential for weather forecasting and other meteorological purposes.