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The Atmosphere in Motion
19 CHAPTER The Atmosphere in Motion EXIT CHAPTER 19.1 Air Pressure and Wind 19.2 Factors Affecting Winds 19.3 Global Wind Patterns 19.4 Continental and Local Winds CHAPTER OUTLINE
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19 19.1 Air Pressure and Wind The Atmosphere in Motion
CHAPTER The Atmosphere in Motion CHAPTER HOME 19.1 Air Pressure and Wind VOCABULARY Air pressure is caused by the weight of the atmosphere over a given area. It is directed equally in all directions. Air pressure is measured with a barometer. air pressure isobar high-pressure area (high) low-pressure area (low) Changes in temperature and humidity change the air pressure. pressure gradient Humid Air Dry Air Nitrogen Oxygen Water Humid air is lighter than dry air because water molecules (H2O) are less massive than oxygen (O2) and nitrogen (N2) molecules. SECTION OUTLINE
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19 19.1 Air Pressure and Wind The Atmosphere in Motion
CHAPTER The Atmosphere in Motion CHAPTER HOME 19.1 Air Pressure and Wind VOCABULARY Winds are caused by differences in air pressure. air pressure isobar high-pressure area (high) Air movement from high pressure areas to low pressure areas low-pressure area (low) pressure gradient SECTION OUTLINE
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19 The Atmosphere in Motion air pressure
CHAPTER The Atmosphere in Motion CHAPTER HOME VOCABULARY air pressure isobar air pressure high-pressure area (high) The force air exerts per unit area. low-pressure area (low) pressure gradient SECTION OUTLINE
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19 The Atmosphere in Motion isobar
CHAPTER The Atmosphere in Motion CHAPTER HOME VOCABULARY air pressure isobar isobar high-pressure area (high) A line on a weather map that joins points having the same barometric pressure. low-pressure area (low) pressure gradient SECTION OUTLINE
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high-pressure area (high)
19 CHAPTER The Atmosphere in Motion CHAPTER HOME VOCABULARY air pressure isobar high-pressure area (high) high-pressure area (high) An area in which the barometric pressure is greater than that of the surrounding air. low-pressure area (low) pressure gradient SECTION OUTLINE
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low-pressure area (low)
19 CHAPTER The Atmosphere in Motion CHAPTER HOME VOCABULARY air pressure isobar low-pressure area (low) high-pressure area (high) An area in which the barometric pressure is lower than that of the surrounding air. low-pressure area (low) pressure gradient SECTION OUTLINE
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19 The Atmosphere in Motion pressure gradient
CHAPTER The Atmosphere in Motion CHAPTER HOME VOCABULARY air pressure isobar pressure gradient high-pressure area (high) The rate at which atmospheric pressure declines over a given distance. low-pressure area (low) pressure gradient SECTION OUTLINE
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19.2 Factors Affecting Winds
CHAPTER The Atmosphere in Motion CHAPTER HOME 19.2 Factors Affecting Winds VOCABULARY Earth’s rotation and curvature cause the Coriolis effect. Coriolis effect jet stream 1. A rocket is fired from the North Pole toward a target near the equator. The rocket goes straight while Earth turns under it. Intended Path Target Rotation of Earth 2. The rocket lands to the west of the target. The Coriolis effect makes the rocket veer off course, to its right. In the Northern Hemisphere, the Coriolis effect turns winds to their right. In the Southern Hemisphere, the Coriolis effect turns winds to their left. SECTION OUTLINE
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19.2 Factors Affecting Winds
CHAPTER The Atmosphere in Motion CHAPTER HOME 19.2 Factors Affecting Winds VOCABULARY Winds blow counterclockwise around lows and clockwise around highs. Coriolis effect jet stream Winds Spiral Clockwise out of a High If there were no Coriolis effect, the wind would blow straight out of a high. The Coriolis effect turns the wind to the right. H Winds Spiral Counterclockwise into a Low If there were no Coriolis effect, the wind would blow straight into a low. The Coriolis effect turns the wind to the right. L Wind direction is also determined by friction with Earth’s surface and air pressure gradients. SECTION OUTLINE
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19 The Atmosphere in Motion Coriolis effect
CHAPTER The Atmosphere in Motion CHAPTER HOME VOCABULARY Coriolis effect jet stream Coriolis effect The effect of Earth’s rotation that causes the deflection of moving objects toward the right in the Northern Hemisphere and toward the left in the Southern Hemisphere. SECTION OUTLINE
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19 The Atmosphere in Motion jet stream
CHAPTER The Atmosphere in Motion CHAPTER HOME VOCABULARY Coriolis effect jet stream jet stream A high-altitude air current forms a narrow band of very strong westerly winds flowing above the middle latitudes; travels up to and beyond 400 kilometers per hour at altitudes of 15 to 25 kilometers. SECTION OUTLINE
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19 19.3 Global Wind Patterns The Atmosphere in Motion
CHAPTER The Atmosphere in Motion CHAPTER HOME 19.3 Global Wind Patterns VOCABULARY Low pressure and rising air are common near the equator. Surface high pressure and sinking air are common at latitudes near 30 degrees and the poles. Earth’s rotation affects wind patterns. These factors are represented in the three-celled model of Earth’s wind patterns. polar front middle latitudes (mid latitudes) intertropical convergence zone (ITCZ) trade winds Three-Celled Circulation Model prevailing winds SECTION OUTLINE
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19 19.3 Global Wind Patterns The Atmosphere in Motion
CHAPTER The Atmosphere in Motion CHAPTER HOME 19.3 Global Wind Patterns VOCABULARY There are wind patterns the three-celled model does not explain. polar front middle latitudes (mid latitudes) Wind Speed Surface winds, August 1, 1999 Knots m/s 50 40 30 20 10 >20 16–18 12–14 8–10 4–6 0–2 18–20 14–16 10–12 6–8 2–4 intertropical convergence zone (ITCZ) The blue areas show winds spiraling around a high. trade winds prevailing winds The yellow areas show winds spiraling around a low. SECTION OUTLINE
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19 19.3 Global Wind Patterns The Atmosphere in Motion
CHAPTER The Atmosphere in Motion CHAPTER HOME 19.3 Global Wind Patterns VOCABULARY There are wind patterns the three-celled model does not explain. polar front middle latitudes (mid latitudes) In the mid-latitudes, surface winds are determined by transient pressure systems. Except near the equator, upper-level winds are generally westerly rather than north or south. intertropical convergence zone (ITCZ) trade winds prevailing winds Uneven heating of Earth by the sun creates pressure zones and wind belts. SECTION OUTLINE
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19 The Atmosphere in Motion polar front
CHAPTER The Atmosphere in Motion CHAPTER HOME VOCABULARY polar front middle latitudes (mid latitudes) polar front The boundary at which air flowing away from the polar regions collides with warmer air from the lower latitudes. intertropical convergence zone (ITCZ) trade winds prevailing winds SECTION OUTLINE
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middle latitudes (mid latitudes)
19 CHAPTER The Atmosphere in Motion CHAPTER HOME VOCABULARY polar front middle latitudes (mid latitudes) middle latitudes (mid latitudes) The area between about 30 degrees and 60 degrees latitude, where surface winds are determined by the locations of transient high- and low-pressure systems. intertropical convergence zone (ITCZ) trade winds prevailing winds SECTION OUTLINE
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intertropical convergence zone (ITCZ)
19 CHAPTER The Atmosphere in Motion CHAPTER HOME VOCABULARY polar front middle latitudes (mid latitudes) intertropical convergence zone (ITCZ) The low-pressure zone at the equator, where the winds from the Northern and Southern Hemispheres converge. intertropical convergence zone (ITCZ) trade winds prevailing winds SECTION OUTLINE
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19 The Atmosphere in Motion trade winds
CHAPTER The Atmosphere in Motion CHAPTER HOME VOCABULARY polar front middle latitudes (mid latitudes) trade winds Steady winds that blow across the equator, from about 30° north latitude to about 30° south latitude. intertropical convergence zone (ITCZ) trade winds prevailing winds SECTION OUTLINE
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19 The Atmosphere in Motion prevailing winds
CHAPTER The Atmosphere in Motion CHAPTER HOME VOCABULARY polar front middle latitudes (mid latitudes) prevailing winds Winds, such as the trade winds and polar easterlies, that usually blow from the same direction. intertropical convergence zone (ITCZ) trade winds prevailing winds SECTION OUTLINE
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19.4 Continental and Local Winds
CHAPTER The Atmosphere in Motion CHAPTER HOME 19.4 Continental and Local Winds VOCABULARY In summer, air over continents has low air pressure and air over seas has high air pressure. Winds tend to blow more from the sea to the continents. The pattern reverses in winter. The reversing winds are called monsoons. monsoon Winter Monsoon ITCZ High Pressure Low Pressure Summer Monsoon ITCZ High Pressure Low Pressure SECTION OUTLINE
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19.4 Continental and Local Winds
CHAPTER The Atmosphere in Motion CHAPTER HOME 19.4 Continental and Local Winds VOCABULARY Local winds along coasts and mountains reverse daily. monsoon Sea-breeze Circulation Warm air rises Cold air descends Land-breeze Circulation Cold air descends Warm air rises SECTION OUTLINE
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19 The Atmosphere in Motion monsoon
CHAPTER The Atmosphere in Motion CHAPTER HOME VOCABULARY monsoon monsoon A wind of Southeast Asia and the Indian Ocean that changes direction seasonally, from the northeast from November until March and the southwest from April until October, when it is accompanied by heavy rains. SECTION OUTLINE
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19 The Atmosphere in Motion I. Air Pressure and Wind
CHAPTER The Atmosphere in Motion CHAPTER HOME VOCABULARY I. Air Pressure and Wind air pressure A. What is Air Pressure isobar 1. Measuring Air Pressure high-pressure area (high) 2. Recording Air Pressure low-pressure area (low) B. Why Does Air Pressure Change pressure gradient C. What Makes the Wind Blow? 1. Measuring Surface Wind Direction and Speed KEY IDEA SUMMARY
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II. Factors Affecting Winds
19 CHAPTER The Atmosphere in Motion CHAPTER HOME VOCABULARY II. Factors Affecting Winds Coriolis effect A. The Coriolis Effect jet stream B. Friction KEY IDEA SUMMARY
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III. Global Wind Patterns
19 CHAPTER The Atmosphere in Motion CHAPTER HOME VOCABULARY III. Global Wind Patterns polar front A. Effects of Earth’s Rotation middle latitudes (mid latitudes) 1. Three-Celled Circulation Model 2. Weaknesses of the Three-Celled Model intertropical convergence zone (ITCZ) 3. Strengths of the Three-Celled Model B. Description of Wind and Pressure Belts trade winds prevailing winds KEY IDEA SUMMARY
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IV. Continental and Local Winds
19 CHAPTER The Atmosphere in Motion CHAPTER HOME VOCABULARY IV. Continental and Local Winds monsoon A. Effects of Seasons and Continents B. Local Winds KEY IDEA SUMMARY
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19 The Atmosphere in Motion
CHAPTER The Atmosphere in Motion CHAPTER HOME This is the end of the chapter presentation of lecture notes. Click the CHAPTER HOME button or exit the presentation.
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