1. Calculating Relative Humidity Practice Use table from MJ 2006 Paper 1 Q4

2. Wet & Dry Bulb Thermometer Wet/Dry Bulb thermometer Hygrometer DRY WET

3. Relative Humidity Table

4. Reminder You need 3 things to calculate the %RH using the table on the previous slide 1.Dry Bulb Temperature 2.Wet Bulb Temperature 3.Depression of the wet bulb (Dry – Wet = Depression of wet bulb)

5. Example 1.Read off thermometers 2.Dry = 28ºC Wet = 25ºC 3.Depression of wet bulb = Dry – Wet 28-25 = 3ºC 4.Read off table Answer = 76% RH

6. Practice DryWetDep%RH A3228 B262 C375 D2273 E264 F281 G2621 H24

7. Answers (Mark out of 16) DryWetDep%RH A3228470 B2624283 C2623375 D2219373 E2622467 F2827191 G2621564 H24 0100