Question

Define (a) relative humidity and (b) temperature . Use your OWN words and (briefly) explain the physical processes involved.   

Plot for DRA 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 hour Relative humidity (%) -temp (degC)

1c) Explain the relationship between temperature and relative humidity as shown in the data sets

1d) Define dew point . Would you expect to observe any dew formation at any time on 21 June 2018 at either site? Explain why/why not.

Answer 1

Relative humidity is the percentage of water vapour present in the air and changes when temperature changes.

a completely saturated parcel of air at constant pressure cannot hold any more water molecules, giving it a relative humidity of 100 percent. As air temperature increases, air can hold more water molecules, and its relative humidity decreases. When temperatures drop, relative humidity increases. High relative humidity of the air occurs when the air temperature approaches the dew point value. Temperature therefore directly relates to the amount of moisture the atmosphere can hold.

When the relative humidity reaches 100 percent, dew forms. Dew point refers to the temperature at which air reaches saturation by water molecules. Warmer air can hold more water molecules, and as that warm air cools, it loses water vapor in the form of condensation. A higher dew point means higher moisture content for air, leading to uncomfortably humid conditions with cloud and precipitation potential. The air itself is saturated once the dew point matches the air temperature. People find dew points of 55 or lower much drier and more comfortable than higher dew points. Dew point never exceeds air temperature. The highest recorded dew point stands at 95 in Saudi Arabia in 2003.

In the firstplot, asthe temperature is increasing, the water _ holding capacity is increasing, leading to more spacefor water molecules. hence reduction in relative humidity. whentemperature is decreasing, the  holding capacity ofwater atmosphere of is decreased to leading increased ordative humidity to concentration of air mass.

In2nd plot, there is not muchgap in temperature& RH But when there is a dip intemperature leads to increase in RH.