1. Chapter 4 Global Climates and Biomes

2. Global Processes Determine Weather and Climate Weather- the short term conditions of the atmosphere in a local area. These include temperature, humidity, clouds, precipitation, wind speed and atmospheric pressure. Climate- The average weather that occurs in a given region over a long period- typically several decades.

3. Earth's Atmosphere Thermosphere temperatures again warm with altitude, rising higher than 1700°C. Mesosphere Temps. fall with increasing altitude - 93°C at an altitude of 85 kilometers. Troposphere- the layer closest to Earth's surface extending roughly 16 km (10 miles) above Earth. Stratosphere- above the troposphere, this extends from roughly 16 to 50 km (10-31 miles). Contains the Ozone layer

4. Atmospheric pressure decreases exponentially as altitude increases. The weight of the air is less. Most of the compressed air is in the lower levels. while temperature rises with altitude in some layers and decreases in others.

5. Unequal Heating of Earth As the Sun's energy passes through the atmosphere and strikes land and water, it warms the surface of Earth. But this warming does not occur evenly across the planet.

6. Albedo effect is light reflected back

7. Unequal Heating of Earth This unequal heating is because: The variation in angle at which the Sun's rays strike The amount of surface area over which the Sun's rays are distributed Some areas of Earth reflect more solar energy than others. (Albedo)

8. Adiabatic heating cooling As air rises pressure decreases. Rising air expands and this lowers the airs temperature When air sinks the pressure increases. Higher pressure decreases the volume and raises the temperature

9. Saturation (Dew) Point As temp increases, saturation point increases.

10. Weather on Earth Causes

11. Atmospheric Convection Currents 1. Air has four properties that determines its movement: Density- less dense air rises, denser air sinks. Water vapor capacity- warm air has a higher capacity for water vapor than cold air. Adiabatic heating or cooling- as air rises in the atmosphere its pressure decreases and the air expands. Conversely, as air sinks, the pressure increases and the air decreases in volume. Latent heat release- when water vapor in the atmosphere condenses into liquid water and energy is released.

12. Sinking air near high-pressure systems inhibits the formation of clouds, so highs are associated with clear, dry weather. Rising air near lows produces clouds and rain.

13. Formation of Convection Currents Hadley Cell- Currents that cycle between the equator and 30 ⁰ N & S ITCZ Intertropical convergence zone. Most intense sunlight Polar Cells currents that are formed by air that rises at 60˚ north and south and sinks at the poles (90˚ north and south)

14. 2. Earth's Rotation and the Coriolis Effect As Earth rotates, its surface moves much faster at the equator than in mid-latitude and polar regions. The faster rotation speed closer to the equator causes a deflection of objects that are moving directly north or south.

15. Earth's Rotation and the Coriolis Effect AnimationAnimation Coriolis Effect- the deflection of an object's path due to Earth's rotation. The winds of the world are produced by a combination of atmospheric convection currents and the Coriolis effect. Strongest at the poles Nonexistant at the equator

16. 3. Pressure Circulation of air around regions of high and low pressure in the Northern Hemisphere WS on Coriolis cyclone v hurricane path Air moves toward low- pressure regions and away from high- pressure regions. The Coriolis force deflects these air masses in opposite directions around highs and lows.

17. Wind Patterns

18. 4. Ocean Currents Sea breezes are caused by temperature differences between land at the surface and adjoining water, which cause air to flow in opposite directions during the day and at night.

20. Ocean Currents Video on Hurricanes 15 minute markHurricanes

21. Ocean Currents Ocean currents are driven by a combination of Temperature, gravity, prevailing winds, the Coriolis effect, and the locations of continents. Warm water, like warm air, expands and rises. Gyres- the large-scale patterns of water circulation. Ocean surface currents rotate in a clockwise direction in the Northern Hemisphere and a counterclockwise direction in the Southern Hemisphere. Why?

22. Mixing of Ocean Water Upwelling- deeper waters rise and replace the water that has moved away also brings up nutrients

23. Thermohaline Circulation Thermohaline circulation- circulation that contains a large amount of salt. drives the mixing of surface water and deep water.

24. Thermohaline Circulation Some of the water that flows from the Gulf of Mexico to the North Atlantic freezes or evaporates, and the salt that remains behind increases the salt concentration of the water. This cold, salty water is relatively dense, so it sinks to the bottom of the ocean, mixing with deeper ocean waters. These two processes create the movement necessary to drive a deep, cold current that slowly moves past Antarctica and northward to the northern Pacific Ocean.

25. El Nino-Southern Oscillation Every 3 to 7 years, the interaction of the Earth's atmosphere and ocean cause surface currents in the tropical Pacific Ocean to reverse direction. These periodic changes in wind and ocean currents are collectively called the EL Nino-Southern Oscillation, or ENSO.

26. La Nina When warm surface water is driven below and replaced with deeper, colder water due to upwelling caused by strong trade winds.

27. 5. Geography It takes a Mountain air moving inland from the ocean that has a large amount of water vapor meets the windward side of a mountain range (the side facing the wind), it rises and begins to experience adiabatic cooling. Due to cooling, the water vapor forms clouds and precipitation falls. the mountain range causes large amounts of precipitation to fall on its windward side. The cold, dry air then travels to the other side of the mountain range (the leeward side), where it descends and experiences higher pressures, which cause adiabatic heating. This air is now warm and dry and cause arid conditions on the leeward side forming the rain shadow. Rain Shadow

28. What causes seasons on the Earth?

29. Earth's Tilt and the SeasonsSeasons The Earth's axis of rotation is tilted 23.5 ˚. When the Northern Hemisphere is tilted toward the Sun, the Southern Hemisphere is tilted away from the Sun, and vice versa.