DPT Relative Humidity Charts Handy Dandy Earth Science

DPT & Relative Humidity Charts Handy Dandy Earth Science Reference Tables Page 12

The “Dry Bulb” n Don’t let it fool you. It is just a thermometer. n It measures the air temperature. n Duh! 20°C

The “Wet Bulb” n Has a little wet booty tied to the bottom. n Gets cool when water evaporates. Wet Booty 12°C

A Dry Day… n. A lot of moisture will evaporate. n The wet bulb will be a lot cooler than the dry bulb. 20°C Difference between wet bulb & dry bulb is 12 °C. 20°C 14°C 12°C 8°C

A Humid Day… n. A little bit of moisture will evaporate. n The wet bulb will not be much cooler than the dry bulb. 20°C Difference between wet bulb & dry bulb is 6 °C. 14°C

Page 12 of your Handy Dandy Earth Science Reference Tables Warning #1: Be sure to READ the correct chart: DPT or RH n Warning #2: Dew Point Temperature IS NOT “Difference between wet bulb and dry bulb”. n Warning #3: The wet bulb temp IS NOT the DPT. n

Dry-bulb temperature is your air temperature. 20 °C

14 °C

4 °C

Subtract (the difference) between the dry bulb and wet bulb

20°C 14°C 20 -14=6

18°C 16°C 18 -16=2

Put it all together 20°C 8°C 20 -8=12 Relative Humidity = 11%

14°C 10°C 14 -10=4 Relative Humidity = 60%

The Dew Point Chart works the same way 14°C 10°C 14 -10=4 Dew Point = 6°C

Try These. Dry Bulb Wet Bulb 26°C 20 °C 6 °C 5 °C 12 °C 8 °C 17 °C 14 °C 0 °C -3 °C R Humidity DPT 57% 86% 57% 91% 100% 45% 17 °C 4 °C 16 °C 14 °C -9 °C

More Difficult. Dry Bulb Wet Bulb 21°C 19°C 11°C 6 °C 17°C 2°C -3 °C 9°C 6. 5 °C 70°F 21 °C 60 °F 15 °C R Humidity DPT 82% 45. 5% 18 °C -. 5 °C 100% 20% 69% 52% 17 °C -17 °C 3. 5 °C 11 °C(50 °F)