Lesson 112

Question 1

Atmospheric pressure in meteorology can be used to:

ISEAR

Answer 1

Identify significant weather patterns
Set aircraft altimeters 
Estimate air motion
Analyze typical atmospheric features 
Relate pressure to weather conditions

Question 2

How is atmospheric pressure calculated?

Formula

Answer 2

pressure = Force / area

Question 3

What are the units involved in the calculation of atmospheric pressure?

Answer 3

Pascels for pressure
Newtons for Force
Meters squared for area

Question 4

What are the values used in the ICAO standard atmosphere?

Answer 4

1013. 25 hPa

29. 92 inches of mercury

Question 5

To arrive at the MSL pressure, the (station pressure) is added to the weight of an imaginary column of air which extends down to MSL. There are two factors that control surface pressure; what are they?

Answer 5

1. Weight of an imaginary column of air which extends down to MSL.
2. Hypothetical temperature (mean of air temperatures now and 12 hours previously).

Question 6

How does heating and cooling affect atmospheric pressure?

Answer 6

Heating = expansion = decreased surface pressure 
Cooling = contraction = increased surface pressure

Question 7

Temperature, pressure, and density vary much greater in the _________ than in the __________.

Answer 7

Vertical

Horizontal

Question 8

One half of the atmosphere’s weight is found below.

Answer 8

500 hPa (approximately 18000’)

Question 9

Standard levels commonly used on constant pressure charts are:

Answer 9

850 hPa, 700 hPa, 500 hPa, 250 hPa.

Question 10

Hydrostatic equilibrium is:

Answer 10

When the vertical component of the pressure gradient force at any given level is in exact balance with the force of gravity at that level.

Question 12

What is the relationship between the thickness of an atmospheric layer and temperature?

Answer 12

Thickness of a layer varies directly with the mean temperature of the layer.

Question 13

Factors affecting the height of a pressure level are (2):

Answer 13

Mean temperature of the column of air under the pressure level.

Value of the MSL pressure.

Question 14

Discuss the pressure and temperature variations found in a:
Cold high
Cold low
Warm low 
Warm high

Answer 14

Draw the slides in lesson

Question 15

Review the seasonal and latitudinal variations in pressure and temperature as they relate to pressure and pressure levels.

Answer 15

Summer to winter - average pressure height in the troposphere becomes lower because the mean temperature in the troposphere becomes colder. Temperature at the low tropopause in winter may be warmer than the temperature at the high tropopause in summer. In winter, pressure levels in the troposphere may be lower than during summer.

Question 16

What are the two factors that control surface pressure?

Answer 16

• a change in temperature

- a change in moisture content (composition of the air)