1. Global Climates and Biomes

2. Global Processes determine weather and climate
Weather – Happens on a time scale of seconds to days
Climate – the average weather that occurs in a given region over a long period of time (decades)
Regional differences in temperature and precipitation help determine where earth’s biomes are located on the planet
This determines which organisms can survive in particular regions of the earth.
To understand these differences, you must understand the processes that affect the distribution of heat and precipitation across the globe.

3. Distribution of biomes

4. Processes that affect biome distribution
Unequal heating of the Earth by the Sun
Atmospheric convection currents
Rotation of the Earth
Earth’s orbit around the Sun on a tilted axis
Ocean currents

5. Earth’s Atmosphere more densely packed closer to the surface
Consists of 5 layers of gases kept in place by gravity.
Because gravitational pull weakens as you move farther from the Earth, molecules are:
more densely packed closer to the surface
less densely packed farther from the surface

6. Troposphere Layer closest to the Earth’s surface
Extends upwards for about 10 miles
Densest layer of atmosphere
Where weather occurs
Air temperature decreases as you move higher into the troposphere

7. Stratosphere Directly above the troposphere
Extends from about 10 to 31 miles upward
Less dense than troposphere
UV radiation reaches higher altitudes first and warms them which means that higher altitudes are warmer than lower altitudes
Ozone (O3)- forms a layer in the stratosphere
Very important because ozone absorbs most of the sun’s UV radiation
This provides critical protection to organisms on the planet.
Stratosphere

8. Unequal heating of the earth
Causes of unequal heating
Variation in the angle that the sun ray’s strike the surface
Variation in amount of surface area that sun rays are distributed
Some areas reflect more solar energy than others

9. Unequal Heating of the earth
Albedo – The percentage of incoming sunlight that is reflected from a surface

10. Properties of Air
The density and temperature of air determines its movement
Less dense, warmer air rises
Denser, colder air sinks

11. Properties of air
Temperature of air affects how much water vapor it can hold
Hot air holds more water vapor
Cooler air holds less water vapor
Saturation Point – the maximum amount of water vapor that can be in air at a given temperature.

12. Properties of Air What does this mean?
Air will rise and fall based on the density
Air will heat and cool based on the pressure
This is called Adiabatic heating and cooling
Air will hold or release water based upon temperature

13. Convection currents
Atmospheric convection currents – global patterns of air movement that are initiated by the unequal heating of the Earth.

14. Formation of convection currents

15. Earth’s Rotation
As Earth rotates, its surface moves much faster at the equator than in mid-latitude and polar regions.
Earth’s tilting rotation is 23.5 degrees.
The faster rotation speeds closer to the equator cause a deflection of objects that are moving directly north or south

16. Earth’s Rotation and the Coriolis Effect
Earth’s rotation has an effect on directions of the prevailing winds
Prevailing winds - a wind from the direction that is predominant at a particular place or season

17. Coriolis Effect Coriolis Effect-
the deflection of an object's path due to Earth's rotation.
an object that moves along a north-south path will undergo apparent deflection to the right in the Northern Hemisphere and to the left in the Southern Hemisphere.

18. The prevailing winds of the world are produced by a combination of atmospheric convection currents and the Coriolis effect.
Hadley Cells – convection currents that cycle between the equator and 30 degrees North and South

19. Convection currents
Hadley Cells: large-scale atmospheric convection cell
air rises at the equator
and sinks at medium latitudes, about 30° north or south.
ITCZ (Intertropical Convergence Zone)
occurs along the equator where there is intense sunlight
Area between 2 Hadley Cells
Intense thunderstorm activity

20. Rain Shadow
Warm, humid air, moves inland from the oceans & hits the windward side of mountains
it begins to rise & cool causing precipitation
the dry cooler air continues to cross the mountains & experience heating as it descends.
This creates distinct climates on both sides of mountains.

21. Variations in Climate Determine the Dominant Characteristics of Each Organism in each Biome
Climate affects the distribution of species around the globe.
Organisms possess distinct growth forms due to adaptations to local temperature and precipitation patterns.