1. Abiotic Factors
Chapter 25, Section 1

2. Environmental Factors
Biotic Factors
Features of an environment that are alive or were once alive.

3. Environmental Factors
Abiotic Factors
Nonliving factors in an environment.
Include:
air, water, soil, sunlight, temperature, and climate.
Often determine which organisms can live in the environment.

4. Air Atmosphere Air that surrounds the Earth Contains:
78% nitrogen
21% oxygen
0.94% argon
0.03% carbon dioxide
Traces of other gases
Air is very important as most organisms need either oxygen or carbon dioxide to live (photosynthesis and respiration).

5. Water
Water
Many life processes, such as photosynthesis, respiration, and digestion require water.
In fact, most organisms are 50% to 95% water.
Environments that have more water usually support a greater diversity of and a larger number of organisms.

6. Soil
Soil
Mixture of minerals, rocks, living and dead organisms, water, and air.
Humus - Decaying matter found in soil.
Soil has an impact on the types of plants that can grow in an environment.

7. Sunlight Sunlight Main energy source in an environment.
Used by producers to make food (sugars).
Transferred to consumers when producers are eaten.

8. Temperature Temperature
Depends on the amount of energy received from the sun
Amount of energy received depends on the latitude and elevation of the area.
Most organisms must maintain a body temperature between 0 and 50 degrees Celsius in order to survive.

9. Temperature
Latitude
Determines the amount of energy received by the sun.
Sunlight strikes the Earth directly at the Equator resulting in large amounts of energy and high temperatures.
Sunlight strikes the Earth at the poles at an angle resulting in smaller amounts of energy and low temperature.

10. Temperature Elevation
Air molecules in the atmosphere trap heat from the sun and serve as a layer of insulation for the Earth.
Because more air molecules are at sea level than are at high elevations temperature decreases with increasing elevation.

11. Climate Climate The average weather conditions in an area.
Includes temperature, precipitation, and wind.

12. Climate
Wind
Movement of air particles from areas of high pressure (cold) to areas of low pressure (warm)

13. Climate Rain Shadow Effect
When air reaches a mountain it is forced upward.
As the air rises, it cools and releases any moisture it contains.
By the time the air reaches the far side of the mountain it is relatively dry.