Exam 2 chapter 5 Flashcards
Average sea level pressure in INCHES?
29.9 inches
1mb = .02953 in of Mercury
The average sea level pressure is…?
1013.25 mb
Average sea level pressure in PASCALS?
101,325 Pa
What does a barometer measure ?
An instrument used to measure air pressure and monitor its change.
2 types of Barometers ?
Mercury Barometer
- Torricelli 1643
- measures expansion and contraction of Mercury that accompany changes in temperature. Also measures slight variation of gravity with latitude and altitude that affects weight of mercury column.
Aneroid (non liquid) Barometer
-used to monitor air pressure. Can be Calibrated to monitor ALTITUDE
What is the set distance to the top of the atmosphere?
None
Sea level is a base measurement of…?
Earths pressure
(Sea-level) How can elevation impact pressure?
Air pressure decreases with increasing altitude (elevation)
Denver vs. Miami??
What is air mass and what are 2 characteristics ?
Air mass is a huge volume of air that is relatively uniform horizontally in temperature and water vapor concentration. As air masses move across the earth, surface air pressures fall or rise and weather changes.
Air pressure falls = stormy weather
Air pressure rises = clear fair weather
Temperature and Humidity in regards to Air Masses
Temperature
-air pressure drops more rapidly with altitude within a cold (denser) column of air than In a warm (less dense) column of air.
Humidity
- The greater the concentration of water vapor, the less dense is the air.
Water vapor reduces the density of air because the molecular weight of water is less than the average molecular weight of dry air.
Cold dry air masses are …?
DENSER and usually produce higher surface pressure than warm human air masses.
Warm dry air masses exert…?
Higher surface pressure than equally warm but more humid air masses.
