Chapter 5 study guideChapter 5 study guide

1.1.      Describe the relationship between atmospheric pressure Describe the relationship between atmospheric pressure and elevation.and elevation.

2.2.      Describe the relationship between temperature and Describe the relationship between temperature and atmospheric pressure.atmospheric pressure.

3.3.      Describe an isobar.Describe an isobar.4.4.      What is wind? Describe the function of the wind on the What is wind? Describe the function of the wind on the

earth.earth.5.5.      What two factors influence wind direction? How do these What two factors influence wind direction? How do these

factors function to influence wind direction?factors function to influence wind direction?6.6.      How are winds named? Define windward, leeward and How are winds named? Define windward, leeward and

prevailing winds.prevailing winds.7.7.      Describe the idealized model of Earth’s pressure and wind Describe the idealized model of Earth’s pressure and wind

systems. (Figure 5.12)systems. (Figure 5.12)

Study Guide Chapter 5Study Guide Chapter 5

8. Define gyres.8. Define gyres.

9.9.      Describe the effects of seasonal migration in Describe the effects of seasonal migration in California.California.

10.10.  What is El Nino?What is El Nino?

11.11.  Describe local winds in our area. (land breeze-Describe local winds in our area. (land breeze-sea breeze, Santa Ana winds, mountain & valley sea breeze, Santa Ana winds, mountain & valley breezes)breezes)

12.12.    Describe the upper air wind system.Describe the upper air wind system.

  

The atmosphere The atmosphere exerts a pressure of exerts a pressure of 14.7lbs/sq in. (1034 14.7lbs/sq in. (1034 grams/cm)grams/cm)

Atmospheric Atmospheric pressure is important pressure is important because variation in because variation in pressure causes our pressure causes our atmospheric atmospheric circulationcirculation

Weight of the AtmosphereWeight of the Atmosphere

Pressure UnitsPressure Units

Meteorologists prefer to Meteorologists prefer to work in millibar (mb) unitswork in millibar (mb) units

Standard sea-level Standard sea-level pressure of 1013.2 mb will pressure of 1013.2 mb will cause mercury to rise to cause mercury to rise to 76 cm or 29.92 inches. See 76 cm or 29.92 inches. See Fig. 5.1 text. Fig. 5.1 text.

Variations in Air PressureVariations in Air Pressure

Air pressure decreases Air pressure decreases with elevationwith elevation

Humans not generally Humans not generally sensitive to small sensitive to small variations in air variations in air pressurepressure

Mapping Pressure DistributionMapping Pressure Distribution

Isobar = lines of equal pressure

The air moves down a pressure gradient. Just like water rolling down a hill from high to low elevation.

Low Atmospheric PressureLow Atmospheric Pressure

High Atmospheric PressureHigh Atmospheric Pressure

Which is High Pressure Which is Low?Which is High Pressure Which is Low?

Cyclones and AnticyclonesCyclones and Anticyclones

Fig 5.3

Horizontal Variation in Air Pressure Horizontal Variation in Air Pressure

Unequal distribution Unequal distribution of insolation results of insolation results in uneven heating of in uneven heating of planet. Pressure and planet. Pressure and temperature. temperature. relationship?relationship?

Other factors include: Other factors include: differential heating of differential heating of land and water, land and water, different albedos of different albedos of surfacessurfaces

5.13

WindWind

Wind is the horizontal movement of air.Winds are named from the direction they are coming from. A North wind is coming from the North.

Fig. 5-7, p. 121

Winds are transportation for energy and moisture. Winds are an attempt to keep the Earth’s temperature in equilibrium.

Fig. 5-13, p. 127

Fig. 5-15, p. 130

Global Wind SystemsGlobal Wind Systems

Subtropical High PressureSubtropical High Pressure Source of Trade Winds and WesterliesSource of Trade Winds and Westerlies Horse LatitudesHorse Latitudes

Trade Winds Trade Winds

5500-25-2500 N and S N and S Northeast and Southeast TradesNortheast and Southeast Trades Pilots flying WestPilots flying West Hawaiian islands pleasantHawaiian islands pleasant

Global Wind SystemsGlobal Wind Systems

ITC (Intertropical Convergence Zone)ITC (Intertropical Convergence Zone) Doldrums (5Doldrums (500N-5N-500S)S) Winds convergeWinds converge Weak winds Weak winds

Idealized modelIdealized model Changes due to land and ocean massesChanges due to land and ocean masses Seasonal changes-pressure belts move North Seasonal changes-pressure belts move North

in summer. in summer.

Coriolis EffectSurface Friction

Effects of Seasonal MigrationEffects of Seasonal Migration

Seasonal migration will Seasonal migration will most affect those regions most affect those regions near the boundary zone near the boundary zone between two wind or between two wind or pressure systemspressure systems

California is an example of California is an example of a region located within a a region located within a zone of transitionzone of transition

5.16

Fig. 5-9, p. 123

Land and Sea Breeze

Mountain & Valley Breezes (local)Mountain & Valley Breezes (local)

Valley breeze Mountain Breeze

5.10

Local WindsLocal Winds

Chinook (USA rocky Chinook (USA rocky mtns)mtns)

Santa Ana- compressed Santa Ana- compressed warm and dry air. warm and dry air.

Foehn wind- AlpsFoehn wind- Alps

5.11

p. 125

Upper Air WindsUpper Air Winds

Include the upper air Westerlies and polar jet Include the upper air Westerlies and polar jet streams. About 16,500 ft. streams. About 16,500 ft.

25-100 miles in width25-100 miles in width 1-2 miles in depth1-2 miles in depth ““Internal ribbon of air” See Fig. 5.19Internal ribbon of air” See Fig. 5.19 Less complex than surface winds.Less complex than surface winds. Fast moving- 100 mph west to east move Fast moving- 100 mph west to east move

weather. weather.

Jet streamsJet streams

Ocean currentsOcean currents

Like winds ocean currents distribute heat and Like winds ocean currents distribute heat and energy of the Earth. energy of the Earth.

Surface currents that move in broad circulatory Surface currents that move in broad circulatory patterns are called gyres.patterns are called gyres.

Ocean currents are affected by the Coriolis Ocean currents are affected by the Coriolis Effect, winds, salinity, and temperature. Effect, winds, salinity, and temperature.

Fig. 5.24

El NiñoEl Niño

El Niño is a warm, weak counter current that replaces the El Niño is a warm, weak counter current that replaces the normally cold (upwelling) coastal watersnormally cold (upwelling) coastal waters

El Niño can last for many months and water El Niño can last for many months and water temperatures are raised for thousands of milestemperatures are raised for thousands of miles

Exceptionally strong El Niños impact worldwide weatherExceptionally strong El Niños impact worldwide weather

El NiñoEl Niño

Sir Gilbert Walker discovers a “seesaw” pattern of air Sir Gilbert Walker discovers a “seesaw” pattern of air pressure in the Pacific called the Southern Oscillationpressure in the Pacific called the Southern Oscillation

Fig. 5-25, p. 140

Interactivity Interactivity

Envrs-chp. 6 number 3. Envrs-chp. 6 number 3.