Lecture 3: Water in the atmosphere 3

Question 1

VAPOUR PRESSURE, SATURATION VAPOUR PRESSURE, AND RELATIVE HUMIDITY- Dalton’s Law of Partial Pressure

Answer 1

Dalton’s Law of Partial Pressure states that the total sum of air pressure inside the parcel is equal to the sum of pressures of the individual gases.

Question 2

VAPOUR PRESSURE, SATURATION VAPOUR PRESSURE, AND RELATIVE HUMIDITY- vapour pressure

Answer 2

Vapour Pressure therefore describes the partial air pressure due to the water vapour contents in the air parcel.
•
The vapour pressure at which the rate of evaporation is equal to the rate of condensation is called Saturation Vapour Pressure – it is a function of the air temperature.

Question 3

EXPLORING THE SATURATED VAPOUR PRESSURE CURVE

Answer 3

The Dew Point Temperature represents the temperature to which air would have to be cooled for saturation to occur.
Warm dew points indicate moist air close to saturation whereas cold dew points indicate dry air.

Question 4

VAPOUR PRESSURE, SATURATION VAPOUR PRESSURE, AND RELATIVE HUMIDITY- humidity

Answer 4

Relative Humidity is the ratio of the amount of water vapour actually in the air to the maximum amount of water vapour required for saturation at that particular temperature.

As such relative humidity only tells us how close air is to being saturated with water vapour, rather than providing information about the actual water vapour contents.