biomes What factors determine biomes?

Global Climates and Biomes Chapter 4

Global Processes Determine Weather and Climate Weather represents short-term, local change in temperature, humidity and precipitation. It can only be predicted a few days in advance Climate is a long-term pattern of average weather that occurs in a region. General predictions can be made. Regional differences in climate determines which organisms can survive in a given region.

atmosphere details more dense at surface of earth 78% nitrogen, 21% oxygen gas, 1% = argon, neon, helium, methane, hydrogen krypton and carbon dioxide. water vapor = 0.4% near earth’s surface

temperature fluctuates greatly Earth’s Atmosphere temperature fluctuates greatly all weather

Name the layers of the atmosphere in order starting at Earth’s surface. In which layer is the ozone located? In which layer does weather occur? What are the major gases and their amounts in the atmosphere Where is the atmosphere most dense? What is ozone? How does the ozone layer affect earth? What class of chemicals depletes ozone? How might soil type affect biomes?

Reasons for the Unequal Heating of Earth Angle of insolation varies the amount of energy that strikes the surface of the Earth. (FIGURE 4.3, PAGE 90) The Sun strikes the tropics at a perpendicular angle. Mid-latitude and polar regions receive solar energy at more oblique angles. Solar energy is lost as it passes through the atmosphere. Solar energy travels shorter distances through the atmosphere at the tropic regions.

Reasons for the Unequal Heating of Earth Variation in the amount of surface area receiving solar energy Light at the mid-latitude and polar regions is distributed over a large surface area, giving each square meter of surface less energy.

Reasons for the Unequal Heating of Earth Different surfaces have different albedo values based on how much light they absorb or reflect. A white surface has a higher albedo than a black surface. Earth has an average albedo value of 30%. The tropics have albedo values that range from 10-20% The snow covered polar regions have albedo values that range from 80%-95% FIGURE 4.4, PAGE 90

Atmospheric Convection Currents Properties of air that determine how it circulates: Density, water vapor, adiabatic heating/cooling and latent heat release. Less dense air rises Warmer air is less dense than colder air Warmer air can hold more water vapor than cooler air. The saturation point is the maximum amount of water vapor that air can hold at a given temperature.

Adiabatic Heating & Cooling In addition to temperature, air responds to changes in pressure. Air under lower pressure expands and this expansion causes the temperature to decrease. This is adiabatic cooling. Adiabatic heating happens when cool air sinks, the pressure increases and this causes the temperature of the air mass to increase.

Latent Heat Release It takes solar energy to convert liquid water to gaseous water vapor. When water vapor condenses back to a liquid this heat is released from the water into the atmosphere.

How Convection Currents Form Global patterns of air movement are initiated by unequal heating of Earth. moist air is warmed and rises at the equator Lower air pressure at high altitudes causes adiabatic cooling, Air reaches saturation Condensation forms clouds This leads to latent heat release Air continues to rise. Adiabatic cooling happens again.

This cold dry air is displaced horizontally to the North and South as warm air continues to rise from the equator. This displaced air eventually sinks at 30ْ N/S. Increased air pressure causes adiabatic heating. This air is hot and dry (leads to deserts) This air moves horizontally to replace the rising air at the equator- completing the cycle. These are called Hadley Cells.

Earth’s Tilt and Seasons The Earth’s axis of rotation is tilted 23.5ْ This causes seasonal changes at the Earth orbits around the Sun

The Coriolis Effect Earth’s rotation influences the directions of prevailing winds . As the Earth rotates, its surface moves much faster at the equator than in mid-latitude and polar regions. This difference in rotation speeds causes a deflection of objects that are moving directly north or south

Global Winds The combination of convection cells and the coriolis effect create distinct wind patterns The trade winds or ‘easterlies’ originate from the east and flow from the 30 N/S latitude towards the equator. The Doldrums are where the trade winds converge at the ITCZ Westerlies are winds that originate from the west and flow pole ward from 30 N/S to 60 N/S. Polar easterlies originate from east and flow from the poles toward lower latitudes. 90 N/S to 60 N/S.

Rain Shadow Effect These are created when global winds carry warm moist air onto the coast and the air mass encounters a mountain range Windward side: Here warm air rises and adiabatic cooling leads to cloud formation and precipitation. Leeward side: Here cold dry air descends and adiabatic heating creates hot dry conditions. Watch this video about Death Valley as an example of the rain shadow effect.

Ocean Currents Influence Climate Currents are driven by a combination of temperature differences, gravity, prevailing winds, the Coriolis effect, and locations of continents. Warm water at the equator rises, while water at mid-latitudes remains at lower elevations. This gradient causes water to flow away from the equator Gyres: Circulation patterns that redistribute heat in the ocean. Flow is clockwise in Northern Hemisphere Flow is counterclockwise in Southern Hemisphere. Watch this video to better understand how ocean currents affect climate

Upwelling: deep waters rise to the surface and circulate nutrients and oxygen. This happens along the western coasts of continents where surface currents diverge. Leads to increased productivity in the ocean. Thermo-haline Circulation: circulation is driven density differences based on temperature and salinity This creates a great ocean conveyor belt that takes hundreds of years to complete. One concern about global warming is that increased ice melt could make the North Atlantic less salty, and less likely to sink. This might shut down thermo- haline circulation. Vertical Circulation

Ocean Currents Transport Heat The Gulf Stream originates in the tropics near the Gulf of Mexico. It flows Northeast and across the Atlantic Ocean towards Europe. It brings heat to higher latitudes that would otherwise be much cooler. Watch this video about the Gulf Stream

El Niño- Southern Oscillation - ENSO Approximately every 3-7 years surface currents in the tropical Pacific Ocean reverse. Movement of warm water and air toward South America suppresses upwelling and decreases productivity. Globally this causes cooler and wetter conditions in the southeast U.S. & dry weather in southern Africa and southeast Asia.

Various Biomes are Identified by the Unique Adaptations in the Dominant Flora & Fauna Plants that grow in a desert biome need to be adapted for hot & dry weather conditions. Plants need to be able to store water and resist evapotranspiration. Organ pipe cactus are found in Arizona. Euphorbia grow in Namibia. They have similar growth pattern as the cactus, but they possess distinctly different flowers and spines. Only members of the Euphorbia family produce a milky sap.

Climate Diagrams Visualize annual temperature and precipitation of a given area or biome. We can look for seasonal patterns. Rainy times of the year Growing season How humans might use different biomes: farming or lumber.