fss 304.1 - atmospheric pressure + associated units of measurements

Atmospheric pressure is the ____ of all air above the point where it was calculated.

weight

Station pressure is the __________ computed at an observing station. Since pressure ______ with height, stations at higher elevations will have a _____ station pressure than those at lower elevations.

actual atmospheric pressure, decreases, lower

Mean sea level (MSL) is used as the standard, to provide a ______.

common reference or datum

In order to calculate pressure at mean sea level from the station pressure, the station pressure is added to the weight of an imaginary column of air that extends from ________ down to _____.

station elevation, MSL

The standard atmospheric pressure value is ______.

hectopascals (hpa)

The International System of units employs Pascals (Pa), Hectopascals (hPa), and Kilopascals (kPa) and inches of mercury (Hg).

Although ______ are a more familiar unit, in terms of value, they are identical to _______.

millibars (mb), hectopascals (hPa)

29.92 inHg = _____ of mercury = _____ mb = _____ hPa

76 cm, 1013.2 mb, 1013.2 hPa

The ________ has a direct impact on its weight; the _____ the air is, the _____ and therefore the lighter it is.

For calculation purposes a mean temperature for the previous ______ is used.

temperature of air, warmer, less dense

12-hour period

In the International Standard Atmosphere (ISA), the average MSL pressure is considered to be:

• _____ inches of mercury (inHg)

• _____ cm of mercury

• _____ mb

• _____ hPa

29.92, 76, 1013.2, 1013.2

Lapse rate is the rate of ________

temperature change with height

Isothermal layer, or ________ has _____ of temperature with height

zero lapse rate, no change

A positive lapse rate has a ______ of temperature with height

decrease

A negative lapse rate, or _____, is an ______ with height.

inversion, increase of temperature

Inversions can lead to ______ being trapped close to the ground. Therefore, expect ______ to occur if an inversion stays in place for an extended period

pollution such as smog, reduced visibilities