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Ch. 6 and 7 Weather, Climate and Biomes Mr. Lesley APES.

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Presentation on theme: "Ch. 6 and 7 Weather, Climate and Biomes Mr. Lesley APES."— Presentation transcript:

1 Ch. 6 and 7 Weather, Climate and Biomes Mr. Lesley APES

2 Weather –The short-term day-to- day changes in temperature, air pressure, humidity, precipitation, sunshine, cloud cover and wind direction and speed. –Most weather is predicted using: weather balloons, aircraft, radar, and satellites

3 Weather Changes –Air Masses: large lump of air that similar temperature and moisture level throughout. –Air Masses that effect the US are

4 When air masses meet it causes changes in weather Cold front: when a cold air mass collides with a stationary warm air mass. The result is: thunderstorms, short bursts of heavy rain

5 Warm Front: when a warm air mass collides with a stationary cold air mass. The result is: warm steady rain

6 Weather is also affected by changes in atmospheric pressure High pressure has descending air that moves outward from the center of the high-pressure system. Descending air is warm and dry. The result is: nice dry weather

7 Low pressure has ascending air that flows towards the center of the low- pressure area. Ascending air- cools and condenses as it rises. The result is: clouds, rain

8 Weather Extremes –Hurricanes: What is it? Tropical storm with winds greater than 75 mph The bad: loss of life and property The good: flushes out coastline

9 Tornadoes: Form when cold dry air collides with warm moist air, which causes the warm air to rise quickly making a funnel cloud

10 Risk of Tornadoes Highest High Medium Low Hurricane Frequency High Moderately high Gulf of Alaska Prince Williams Sound CANADA UNITED STATES Grand Banks Atlantic Ocean MEXICO Fig. 6.2, p. 122

11 Climate –Climate is the long term average precipitation and temperature of an area –Climate is determined by global wind patterns, latitude, altitude and ocean currents

12 Climate the average weather patterns for an area over a long period of time (30 - 1,000,000 years). is It is determined by Average Precipitation Average Temperatureand which are influenced by latitudealtitudeocean currents and affects where people livehow people live what they grow and eat Fig. 6.3, p. 123

13 Polar (ice) Subarctic (snow) Cool temperate Warm temperate Dry Tropical Highland Major upwelling zones Warm ocean current Cold ocean current River Fig. 6.4, p. 124

14 Global Air currents affect regional climates Uneven heating of the Earths surface causes the equator to receive more sunlight making it hotter; the poles receive less light making them cooler. This causes: global circulation

15 Fig. 6.6b, p. 125 Initial pattern of air circulation Deflections in the paths of air flow near the earths surface 30°S Easterlies Westerlies Southeast tradewinds (Doldrums) Northeast tradewinds Westerlies (from the west) Easterlies (from the east) 60°S equator 30°N 60°N

16 Climate type Cold Cool Temperate Warm Temperate Tropical (equator) Tropical Warm Temperate Cool Temperate Cold Fig. 6.6a, p. 125

17 Seasons Seasonal changes in temp and precipitation affect climate because the earth is tilted on its axis. It is colder in the winter and warmer in the summer because:

18 Fall (sun aims directly at equator) Summer (northern hemisphere tilts toward sun) Spring (sun aims directly at equator) 23.5 ° Winter (northern hemisphere tilts away from sun) Solar radiation Fig. 6.5, p. 124

19 Coriolis Effect Rotation of the Earth on its axis prevents air currents from moving directly north or south causing the winds to curve in what is called:

20 Ocean Currents Long term variations in the amount of incoming solar radiation Heat from the sun evaporates water and transfers energy from the ocean to the atmosphere. This creates convection cells that transport heat to different latitudes. This leads to: ocean currents and weather

21 Polar (ice) Subarctic (snow) Cool temperate Warm temperate Dry Tropical Highland Major upwelling zones Warm ocean current Cold ocean current River Fig. 6.4, p. 124

22 –Ocean Currents Affect climate Differences in water temp, winds and the rotation of the earth create currents. Currents redistribute heat. For example the gulf stream brings heat to Europe

23 Upwelling is created when the trade winds blow offshore pushing surface water away from land. The outgoing surface water is replaced by nutrient bottom water. Upwelling support:

24 Wind Movement of surface water Diving birds Nutrients Upwelling Fish Zooplankton Phytoplankton Fig. 6.9, p. 126

25 The El Nino Southern Oscillation occurs every few years in the Pacific Ocean –In an ENSO, prevailing westerly winds weaken or stop –Surface waters along the coast of North America and South America (west) become warmer –Normal upwelling stops –This reduces the population of some fish species –Also causes severe weather, storms in the US especially CA, and drought in southeast Asia

26 Normal Conditions Cold water Warm water Thermocline SOUTH AMERICA Warm waters pushed westward AUSTRALIA EQUATOR Surface winds blow westward Fig. 6.10a, p. 127

27 1982–831997–98 Year El Nino conditions La Nina conditions Temperature/Change (°F) Fig. 6.12, p. 128

28 El Niño Conditions Cold water Thermocline Warm water Warm water deepens off South America SOUTH AMERICA Warm water flow stopped or reversed AUSTRALIA EQUATOR Drought in Australia and Southeast Asia Winds weaken, causing updrafts and storms Fig. 6.10b, p. 127

29 El Niño Unusually warm periods Unusually high rainfall Drought Fig. 6.11, p. 127

30 La Nina La Ninas follow an El Nino and are characterized by cooling trends. La Nina brings more Atlantic hurricanes, colder winters in the north and warmer winters in the south, and an increase in tornadoes.

31 The chemical makeup of the atmosphere affects the weather. Small amounts of water vapor, carbon dioxide, ozone, methane, nitrous oxide and chlorofluorocarbons trap heat in the atmosphere warming the planet. These gases are called: greenhouse gases The greenhouse effect is when greenhouse gases allow light, infrared radiation and UV radiation through to the surface of the earth where it is reflected back into space. The greenhouse gases trap some reflected infrared radiation

32 Rays of sunlight penetrate the lower atmosphere and warm the earth's surface. The earth's surface absorbs much of the incoming solar radiation and degrades it to longer-wavelength infrared radiation (heat), which rises into the lower atmosphere. Some of this heat escapes into space and some is absorbed by molecules of greenhouse gases and emitted as infrared radiation, which warms the lower atmosphere. As concentrations of greenhouse gases rise, their molecules absorb and emit more infrared radiation, which adds more heat to the lower atmosphere. (a)(b)(c) Fig. 6.13, p. 128

33 Ozone Layer The ozone layer is located in the stratosphere. It is created when ultraviolet light turns oxygen into ozone. The chemical reactions is: –Ozone blocks all short wavelength UV-C radiation, 50% of the UV-B radiation and almost no long wavelength UV-A radiation. –Ozone also forms a thermal cap which: traps heat

34 Topography of the earth also creates microclimates A microclimate is small area that has a different climate than the general climate of an area. –Vegetation in an area influences climate: forests stay warmer in the winter and cooler in the summer because of the trees – Cities create heat islands that trap heat and decrease wind speeds

35 Cool air descends Land warmer than sea; breeze flows onshore Warm air ascends Fig. 6.15a, p. 130 Water also changes climate by causing land breezes and sea breezes

36 Warm air ascends Land cooler than sea; breeze flows offshore Cool air descends Fig. 6.15b, p. 130

37 a Winds carry moisture inland from Pacific Ocean b Clouds, rain on windward side of mountain range c Rain shadow on leeward side of mountain range Moist habitats 15/25 1,000/85 1,800/125 3,000/85 4,000/75 1,000/25 2,000/25 Fig. 6.14, p. 129 The rain shadow effect changes climate

38 Dry woodlands and shrublands (chaparral) Temperate grassland Temperate deciduous forest Boreal forest (taiga), evergreen coniferous forest (e.g., montane coniferous forest) Arctic tundra (polar grasslands) Tropical savanna, thorn forest Tropical scrub forest Tropical deciduous forest Tropical rain forest, tropical evergreen forest Desert Ice Mountains (complex zonation) Semidesert, arid grassland Tropic of Capricorn Equator Tropic of Cancer Fig. 6.16, p. 131

39 Polar Subpolar Temperate Tropical Desert Deciduous forest Deciduous forest Coniferous forest Chaparral Grassland Savanna Scrubland Tropical seasonal forest Tropical seasonal forest Rain forest Tundra Fig. 6.17, p. 132

40 Alpine Tundra Montane Coniferous Forest Deciduous Forest Tropical Forest Tropical ForestTemperate Deciduous Forest Northern Coniferous Forest Arctic Tundra LowHighMoisture Availability High Low Elevation Fig. 6.18, p. 133

41 Plant and animal adaptations to climate –For plants precipitation is generally the limiting factor in determining whether a climate is a desert, forest or grassland, but biomes are not uniform. They have the same general characteristics but there are microclimates that determine the actual plants you will find in any given area.

42 Plants exposed to cold year around or in the winter have: Traits that keep them from losing too much heat or water They stay small

43 Desert plants must be able to lose heat and conserve water. They do this by: Lose heat and store water Fleshy tissue, vertical, no leaves, store water

44 In wet tropical climates the plants have Broadleaf evergreen, maximize sunlight

45 In climates that are hot in summer and cold in winter, plants have: Deciduous leaves that fall off in winter

46 In areas with cool short summers, the trees have: Coniferous evergreen Needle shaped leaves

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