The Stevenson Screen

That box is called a Stevenson Screen, a ventilated area for delicate instruments to be housed in.

The Stevenson Screen was designed and built from scratch using composites and vents. Invented in the 1800s by Sir Thomas Stevenson, the rigid structure provides the instruments with a secure shelter from winds, rain and snow, while the vents allow for maximum airflow. Also, the box gives the instruments shade so the instruments are not affected by solar radiation. This makes the instrument readings most accurate. In my design, the board containing the instruments is offset from the back of the weather station to avoid the conduction of heat from the board. Holes from the bottom allow for airflow and also for drainage if any rain from a storm comes in. The spacing between the vents do not allow large objects inside the screen, but students can see through the slats at the readings on the instruments inside the Stevenson Screen.

On a hot sunny day, thermometers can be quite inaccurate if they are placed in direct sunlight or mounted on material that absorbs heat from the sun. On this weather station, there are three thermometers: one on the clock, one liquid tube, and one in the Stevenson screen. As an example, two images below show the temperature readings at the same time. The thermometer on the left is outside the Stevenson screen and the one on the right is inside the screen. As you can see, they are more than six degrees apart from each other. The one inside the Stevenson screen is showing the accurate ambient temperature. Measured humidity is also affected by the sun, so expect a difference in the readings of humidity on the clock and in the Stevenson Screen.