3B2 Recap on Weather & Climate (RH & Cloud Formation)

When air is saturated, and RH = 100%

This means that current amount of water vapour in the air is the same as maximum amount of water vapour that can be held in the air

1. Dip the wick of the wet bulb thermometer in water

2. Use wrist action to rotate the sling at a steady pace, about 2 turns per second. Keep psychrometer far from body. Sling the instrument for about a minute.

3. After 1 minute, stop, read and record the temperature on wet bulb thermometer.

4. Continue swinging the sling psychrometer for another minute, stop, read and record the temperature on the wet bulb thermometer

5. Read and record the temperature on the dry bulb thermometer

6. Calculate the difference between the dry bulb and wet bulb temperatures. Refer to the RH chart to find out the RH

Make sure the wet bulb wick is fully saturated with clear water. Do not hold the wick with your hands. Why?

Stand in a shady spot. Why?

•Keep the sling psychrometer far enough from your body and face into the wind. Why?

•Be careful with the sling psychrometer and don’t hit any objects