Dew Point

Question 1

Moisture is added to unsaturated air through the processes of….

Answer 1

Evaporation (liquid water turning to gaseous water)
OR
Sublimation (solid water/ice turning to gaseous water/water vapor)

Question 2

The dew point is….

Answer 2

The temperature at which the air must be cooled to reach it’s maximum level of water vapor saturation.

Question 3

Once the air temperature reaches the dew point….

Answer 3

The air is saturated with moisture which forms fog and clouds which significantly reduces visibility, adds to icing dangers and more.

Question 4

Pilots can estimate the base of clouds by using….

Answer 4

the reported dew point spread.

Question 5

The temperature dewpoint spread decreases by what rate when altitude increases?

Answer 5

-2.5 Degrees celsius per 1000’

Question 6

The moist adiabatic lapse rate is known to be

Answer 6

-1.5 degrees celsius per 1000’

Question 7

The dry adiabatic lapse rate is known to be

Answer 7

-3.0 degrees celsius per 1000’

Question 8

In aviation, we assume a parcel of air is adiabatic, meaning….

Answer 8

it has not heat entering or leaving the parcel.

Question 9

The standard adiabatic lapse rate is known to be

Answer 9

-2.0 degrees celsius per 1000’

Question 10

To find cloud base, we use…

Answer 10

the dry adiabatic lapse rate (-3.0 degrees celsius per 1000’) minus the dew point lapse rate (.5 degrees celsius per 1000’). This means that the temperature/dew point spread in a dry adiabatic parcel of air has a lapse rate of -2.5 degrees celsius per 1000’

Question 11

The actual lapse rate compared to the standard/average lapse rate can tell you what?

Answer 11

Information on the stability of the atmosphere. A higher change in temperature per change in altitude means more changes in pressure per altitude, more air movement, more wind shear, and more instability.

Question 12

What is the temperature/dew point spread lapse rate in farenheit?

Answer 12

-4.5 degrees Fahrenheit per 1000’br14