Jeppesen Aviation Weather Chapter 3: Pressure, Altitude, And Density

Front 1

Absolute Altitude

Back 1

-The altitude of an aircraft above the ground.

Front 2

Bermuda High

Aleutian Low

Siberian High

Icelandic Low

Pacific High

Back 2

What are the larger semi-permanent pressure systems?

Front 3

Altimeter Errors

Back 3

-There are three specific errors caused by nonstandard atmospheric conditions: 1) Sea level pressure different from 29.92 in. Hg., 2) Temperature warmer or colder than standard temperature, 3) Strong vertical gusts.

Front 4

Altimeter Setting

Back 4

-The value to which the scale of a pressure altimeter is set so as to read true altitude at field elevation.

Front 5

Aneroid Barometer-

Back 5

-An instrument for measuring atmospheric pressure. Its key component is a partially evacuated cell which changes dimensions in proportion to the change in atmospheric pressure.

Front 6

Aneroid Cell-

Back 6

-A closed vessel that is part of the aneroid barometer system.

Front 7

Atmospheric Pressure

Back 7

-The weight of a column of air (per unit area) above the point of measurement.

Front 8

Constant Pressure Charts

Back 8

-A weather chart that represents conditions on a constant pressure surface; may contain analyses of height, wind, temperature, humidity, and/or other elements.

Front 9

Contours

Back 9

-A line of equal height on a constant pressure chart.

Front 10

Density Altitude

Back 10

-The altitude above mean sea level (MSL) at which a given atmospheric density occurs in the standard atmosphere.

Front 11

Height Gradient

Back 11

-The rate of change of height per unit of distance on a constant pressure chart.

Front 12

High

Back 12

-An area of high barometric pressure, with its attendant system of winds; an anticyclone. Also called a high-pressure system.

Front 13

Hydrostatic Balance

Back 13

-The balance between the downward-directed gravitational force and an upward-directed vertical pressure gradient force.

Front 14

Indicated Altitude

Back 14

-Altitude as measured by the altimeter.

Front 15

Isobars

Back 15

-Lines of constant barometric pressure.

Front 16

Low

Back 16

-An area of low barometric pressure, with its attendant system of winds. Also called a cyclone.

Front 17

Mercurial Barometer

Back 17

-A barometer in which pressure is determined by balancing air pressure against the weight of a column of mercury in an evacuated glass tube.

Front 18

Pressure Altimeter

Back 18

-An aneroid barometer with a scale graduated in altitude instead of pressure using standard atmospheric pressure-height relationship; shows indicated altitude (not necessarily true altitude); may be set to measure altitude (indicated) from any arbitrarily chosen level.

Front 19

Pressure Altitude

Back 19

-The altitude of a given pressure surface in the standard atmosphere.

Front 20

Pressure Gradient

Back 20

-The difference in pressure between two points at a given time, divided by the distance over which the difference occurs (e.g., units of inches/statute miles or millibars/km).

Front 21

Ridge

Back 21

-An elongated area of relatively high atmospheric pressure; usually associated with and most clearly identified as an area of maximum anticyclonic curvature of the wind flow (isobars, contours, or streamlines). Also called a ridge line.

Front 22

Sea Level Pressure (SLP)

Back 22

-The atmospheric pressure at mean sea level.

Front 23

Station Pressure

Back 23

-The actual atmospheric pressure at the observing station.

Front 24

Surface Analysis Chart

Back 24

-A chart which shows pressure as well as other meteorological conditions at the surface of the earth.

Front 25

Trough

Back 25

-Appears on surface analysis charts and constant pressure charts as elongated areas of relatively low atmospheric pressure or height. Generally associated with cyclonic curvature of the wind flow.

Front 26

True Altitude

Back 26

-The actual altitude of an aircraft above mean sea level (MSL).

Front 27

It is small and rugged; that is, it can be carried in an aircraft where it can withstand strong g-forces due to atmospheric turbulence and maneuvering.

Back 27

-What are some advantages of the aneroid barometer over the mercurial barometer?

Front 28

Station pressure is the pressure at the station measuring it, but these stations can be located at different altitudes. Sea level pressure is the pressure at an altitude above sea level and is often station pressure corrected for elevation.

Back 28

-What is the difference between station pressure and sea level pressure?

Front 29

Trough

Back 29

-High : Ridge :: Low : _______

Front 30

close together; spaced far apart

Back 30

-If the pressure gradient is strong, isobars will be ______________. If the pressure gradient is weak, the isobars will be ________________.

Front 31

Isobars(2)

Back 31

-On a surface analysis chart, the solid lines that depict sea-level pressure patters are called __________.

Front 32

contours; isobars

Back 32

-On constant pressure surfaces, lines of constant height are called __________ rather than _________ such as on a surface analysis chart.

Front 33

By adjusting your Kollsman window to 29.92

Back 33

-When flying your aircraft, how can you determine the pressure altitude?

Front 34

Aneroid barometer

Back 34

-The altimeter is essentially a(n) _________________ that reads in units of altitude rather than pressure.

Front 35

TRUE the actual state of the atmosphere is the same as the standard atmosphere, then the pressure altitude is equivalent to the actual altitude.

Back 35

-T/F: If the actual state of the atmosphere is the same as the standard atmosphere, then the pressure altitude is equivalent to the actual altitude.

Front 36

True. altitude is the actual altitude of your aircraft above MSL and absolute altitude is your actual altitude above the ground.

Back 36

-What is the difference between true altitude and absolute altitude?

Front 37

1) Sea level pressure different from 29.92 in. Hg.

2) Temperature warmer or colder than standard temperature.

3) Strong vertical gusts.

Back 37

-Name the three specific altimeter errors caused by nonstandard atmospheric conditions.

Front 38

29.92 in. Hg

Back 38

-In U.S. airspace at flight levels at and above 18,000 feet, what are the altimeters set to?

Front 39

False-Atmospheric pressure DECREASES with altitude more rapidly in cold air than in warm air

Back 39

-T/F: Atmospheric pressure increases with altitude more rapidly in cold air than in warm air.

Front 40

hourly observation;

Back 40

Aviation routine weather report or METAR:

Front 41

Aviation selected special weather report or SPECI: special, unscheduled report indicating a significant change in one or more elements.

Back 41

-What are the two types of weather reports?

Front 42

"K"

Back 42

-On a METAR report in the contiguous 48 states, what letter prefixes the three-letter domestic location identifier?

Front 43

The day of the month

Back 43

-On a METAR report, what does the two-digit date number stand for?

Front 44

UTC or Zulu

Back 44

-On a METAR report, the time is given in either _____ or _____.

Front 45

"AUTO"

Back 45

-When a METAR is created by a totally automated weather observation station, what modifier is used?

Front 46

To indicate a corrected METAR which replaces a previously disseminated report.

Back 46

-When is the modifier "COR" used on a METAR report?

Front 47

No modifier is used.

Back 47

-What modifier is used when a manual station or manual input at an automated station is used on a METAR report?

Front 48

Temperature in Celsius/Dew point in Celsius.

Back 48

-What do the digits "18/09" stand for on a METAR report?

Front 49

"M" to indicate minus.

Back 49

-What prefix is used for temperatures below 0 deg Celsius on a METAR report?

Front 50

Reported in inches of mercury in a four digit group without the decimal point, and is prefixed by an "A." Internationally, it is reported the same way but in millibars and prefixed with a "Q."

Back 50

-How is the altimeter setting reported on a METAR report?

Front 51

With "RMK."

Back 51

-How does the remarks section begin on a METAR report?

Front 52

Sea Level Pressure of 1013.4 hPa. The leading 9 or 10 is omitted

Back 52

-On a METAR report, what does the remark "SLP134" mean?

Front 53

Refers to the temperature and dew point in tenths deg Celsius. In this example, the first zero in the sequence indicates a plus value for temperature (+.8 deg C) and the leading "one" in the sequence shows a minus value for dew point (-1.6 deg C).

Back 53

-On a METAR report, what does the remark "T00081016" mean?

Front 54

TRUE

Back 54

-T/F: Pressure altitude and density altitude have the same value at standard temperature in the standard atmosphere.

Front 55

Humid air is LESS dense than dry air at the same pressure and temperature

Back 55

-T/F: Humid air is more dense than dry air at the same pressure and temperature.

Front 56

pressure; nonstandard temperature differences

Back 56

-Density altitude is _________ altitude corrected for ___________________.

Front 57

"High" meaning the operation of your aircraft in a high density altitude condition is equivalent to taking off from a higher airport during standard conditions.

Back 57

-In warmer-than-standard surface conditions, you would say that the density altitude is ______.

Front 58

2,116.8 lbs

Back 58

-What is the total weight of the atmosphere (in pounds) over an area of one square foot at sea level in the standard atmosphere?

Front 59

The true altitude would be less than indicated.

Back 59

-If your altimeter setting was correct on takeoff and the sea level pressure decreased along your flight track, how would your true altitude change relative to your indicated altitude during the flight?

Front 60

hydrostatic balance

Back 60

-the balance between the downward-directed gravitational force and an upward-directed force caused by the decrease of atmospheric pressure with altitude?

Front 61

Hydrostatic balance.(2)

Back 61

-The air parcel resists any change in vertical movement because the forces acting on it tend to be equal and opposite. However, the parcel can still be accelerated horizontally under these circumstances

Front 62

14.7

29.92 inches

Back 62

-A sea level pressure of ____________ lbs/in2 will force the mercury to a height of _______________above the reference

Front 63

The aneroid barometer.

Back 63

-Pressure changes cause the aneroid cell to deform in a predictable manner. The changes are mechanically linked to the pressure scale on the right

Front 64

close together

spaced far apart

Back 64

-If the pressure gradient is strong, isobars will be______________ ; if the gradient is weak, the isobars will be-________________ .

Front 65

constant height surface

Back 65

-A horizontal plane where the altitude (MSL) is the same at all points.

Front 66

constant pressure surface

Back 66

-Where the pressure is the same at all points.

Front 67

indicated altitude

decrease

Back 67

-Increasing the altimeter setting will cause the to __________________to increase, while decreasing the altimeter setting will cause the indicated altitude to ________________?

Front 68

absolute altitude

true altitude

indicated altitude

Back 68

-What are the types of altitude measured by your altimeter

Front 69

1.Sea level pressure different from 29.92 inches of mercury. 2.Temperature warmer or colder than standard temperature. 3.Strong vertical gusts.

Back 69

-What are three specific altimeter errors caused by nonstandard atmospheric conditions?

Front 70

millibars (hectopascals)

Back 70

-Internationally, altimeter settings are given in?

Front 71

true altitude

Back 71

-Altimeter setting is the value to which the barometric pressure scale on the altimeter is set so the altitude indicates________________ at field elevation.

Front 72

is lower than true altitude

Back 72

-On warm days pressure surfaces are raised and the indicated altitude ___________________?

Front 73

density altitude

Pressure altitude

Back 73

-__________and_____________ have the same value at standard temperature in the standard atmosphere

Front 74

...

Back 74

-What is the total weight of the atmosphere (in pounds) over an area of one square foot at sea level in the standard atmosphere?

Front 75

...

Back 75

-You are flying at an indicated altitude of 3,000 feet MSL over a region where there is a strong high pressure area at the surface. Sea level pressure is 1046 mb. Your altimeter is set at 29.92. For simplicity, assume that the atmosphere is at standard temperature and there are no other errors in measurement. Estimate your true altitude?

Front 76

...

Back 76

-Calculate the density altitude of an airport located at 2,000 feet MSL with an altimeter setting of 29.92 and a temperature of 95°F. Use a flight computer or density altitude chart.

Front 77

...

Back 77

-Do the computation in problem 3 for the same airport, but for a temperature of 104°F and an altimeter setting of 29.80 in. Hg.

Front 78

...

Back 78

-If you set your altimeter at 29.92 inches and fly at an indicated altitude of 9,882 feet, what is the atmospheric pressure at flight level?

Front 79

...

Back 79

-In Question 5, will your true altitude also be 9,882 feet?

Front 80

...

Back 80

-If your altimeter setting was correct on takeoff and the sea level pressure decreased along your flight track, how would your true altitude change relative to your indicated altitude during the flight?