GEOG 2050 Chapter : Chapter 6, 7, 9 Exam 3
Chapter 6 in class notes 10/14/2013 5:22:00 PM
Key Concepts
• Air pressure
• Mercury Barometer
• Aneriod Barometer
• Wind
• Anemometer
• Wind vane
• Beaufort wind scale
• Isobars
• Pressure Gradient force
• How do we determine air movement?
Tambora
• Eruption 1815
• Volcanic explosively index (VEI)(1-8)
• 1816 “The year without a summer”
• agricultural crops failed and livestock died
o the worst famine of the 19th century
o sunsets had bright vivid colors due to dusk scattering in the
atmosphere
atmospheric Circulation
• Mt. Pinatubo erupts
o June 1991
o 2nd largest eruption in 20th century VEI=6
Air Pressure
• Molecules in air create pressure
• Gas laws
o P=RpT
▪ P=pressure
▪ T=temperature
▪ P=Density
=Mass/Volume
▪ R=gas constant
Mercury Barometers
• Early way to measure pressure
Aneroid Barometer
• How we measure pressure today
Air pressure Measurements
• Milibar (mn or mbar)***
o Force per m Squared
o Commonly used in meterology/Weather
• Pascals (Pa)
o 1kPa=10Mbar
o scientific
• atmosphere (atm)
o SI unit
o 1 atm=1013.25 mbar
• mmHg or inches of Hg
o mbar*0.02953 =inches of Hg
• PSI (pounds square inch)
• Measured with barometers
• Range
o 890 to 1050 mbar
• average sea-level pressure (slp)
o 1013.25 mbar
o 29.92 mmHg
o 101.32 kPa
• Changes in Pressure are least noticeable, but are important in
producing weather!
Air Pressure Readings
• Lowest in US, 882 mbar
o Hurricane Wilma 2005
• Earth’s record low, 870 mbar
o Typhoon Tip Oct. 1979
• Highest in US, 1065 mbar
o Barrow AK Jan 1970
• Earth’s records high, 1084 mbar
o Siberia, Dec 1968
Wind
• Movement of air
• Measure speed
o Anemometer
o Miles per hour (mph)
o Kilometer per hour (kmph)
o Meters per second (mps)
o Knots (Nautical mile/hour)
• Measure direction
o Wind vane
o 10m (33ft) above surface
Wind direction
• Meteorology
o Direction the wind is from
▪ Westerly wind from the west
• Degrees from North
o Westerly wind is 270 degrees
▪ Figure 6.5
Beaufort Wind Scale –weekly activity
• Developed in 1806 by Sir Francis Beaufort of England
• Describe wind from wave observation, developed later for land
o Table 6.1
Ocean
• Pressure increases with depth
• 1 decibars (dbar) =~1m
• depth can be determined by pressure
• Currents (Similar to wind)
o Current meters
▪ Speed
▪ Direction
Energy budget by latitude
• Unequal heating different densities, air masses move to reach
equilibrium
Convection
• Major way we move energy around the atmosphere
Driving Forces of Wind/Ocean –GOLD STAR!!!
• Gravity
o ~uniform world wide
o holds temperature
• Pressure gradient force
o High to low pressure
Document Summary
Pinatubo erupts: june 1991, 2nd largest eruption in 20th century vei=6. Air pressure: molecules in air create pressure, gas laws, p=rpt, p=pressure, t=temperature, p=density. Mercury barometers: early way to measure pressure. Aneroid barometer: how we measure pressure today. Air pressure readings: lowest in us, 882 mbar, hurricane wilma 2005, earth"s record low, 870 mbar, typhoon tip oct. 1979, highest in us, 1065 mbar, barrow ak jan 1970, earth"s records high, 1084 mbar, siberia, dec 1968. Wind: movement of air, measure speed, anemometer, miles per hour (mph, kilometer per hour (kmph, meters per second (mps, knots (nautical mile/hour, measure direction, wind vane, 10m (33ft) above surface. Wind direction: meteorology, direction the wind is from, westerly wind from the west, degrees from north, westerly wind is 270 degrees, figure 6. 5. Beaufort wind scale weekly activity: developed in 1806 by sir francis beaufort of england, describe wind from wave observation, developed later for land, table 6. 1.
