Chapter 39: Biomes
39.1 The Physical Environment Determines Where Life Exists
● Biomes are major types of ecosystems on land characterized by a particular
climate and a distinctive group of species. Examples include forests, deserts,
and grasslands.
● Lakes, streams, and oceans are water-based ecosystems
● Abiotic factors influence the species composition of an ecosystem
● Primary producers provide food for other organisms in the ecosystem. The
types of primary producers an ecosystem can support are influenced by
abiotic factors.
o Plants are the main primary producers of biomes on land. Species
composition is influenced by climate
o In the water, the major primary producers are phytoplankton:
microscopic, free-floating photosynthetic organisms such as
cyanobacteria and algae
39.2 Earth Has Diverse Climates
Climate – long-term weather patterns at a location. Climate includes average
conditions and seasonal differences.
Earth is tilted on its axis at an angle of approximately. 23.5 degrees!
A. Effect of Latitude on Temperature
● Some important latitudes:
o 0°: Equator
o 23.5°N: Tropic of Cancer
o 23.5°S: Tropic of Capricorn
o 90°N and 90°S: North and South Poles
, Angle of Incidence: angle in which the sun rays strike the
earth; because the earth is curved, this angle is different at
different distances from the equator.
Near the equator: at its highest point during the day, the sun is directly
overhead. The angle of incidence is 90 degrees. Energy is concentrated in a
smaller area than near the poles
Near the pole: The sun is directly overhead. Energy is spread over larger
areas: colder because energy is over larger areas; f7e to earth's curvature.
B. Seasonality The earth is tilted on its axis at an angle of
approximately 23.5°. As the earth revolves around the sun, tilt and
latitude determine seasons.
Solstices and Equinoxes are named for the season in the northern hemisphere.
Month Earth’s tilt Latitude where Hours of daylight
relative to the sun is
the sun directly
overhead (90°
angle of
incidence)
Summer
Solstice June Northern 23.5 Degrees
Hemisphere North 24 Hours of light near
towards the Tropic of the North Pole
sun Cancer
Most hours of daylight
in Northern
Hemisphere
24 Hours of dark near
the South Poles
Shorter days in the
Southern Hemisphere
Days lengths begins
shortening, continues
until Winter Solstice
39.1 The Physical Environment Determines Where Life Exists
● Biomes are major types of ecosystems on land characterized by a particular
climate and a distinctive group of species. Examples include forests, deserts,
and grasslands.
● Lakes, streams, and oceans are water-based ecosystems
● Abiotic factors influence the species composition of an ecosystem
● Primary producers provide food for other organisms in the ecosystem. The
types of primary producers an ecosystem can support are influenced by
abiotic factors.
o Plants are the main primary producers of biomes on land. Species
composition is influenced by climate
o In the water, the major primary producers are phytoplankton:
microscopic, free-floating photosynthetic organisms such as
cyanobacteria and algae
39.2 Earth Has Diverse Climates
Climate – long-term weather patterns at a location. Climate includes average
conditions and seasonal differences.
Earth is tilted on its axis at an angle of approximately. 23.5 degrees!
A. Effect of Latitude on Temperature
● Some important latitudes:
o 0°: Equator
o 23.5°N: Tropic of Cancer
o 23.5°S: Tropic of Capricorn
o 90°N and 90°S: North and South Poles
, Angle of Incidence: angle in which the sun rays strike the
earth; because the earth is curved, this angle is different at
different distances from the equator.
Near the equator: at its highest point during the day, the sun is directly
overhead. The angle of incidence is 90 degrees. Energy is concentrated in a
smaller area than near the poles
Near the pole: The sun is directly overhead. Energy is spread over larger
areas: colder because energy is over larger areas; f7e to earth's curvature.
B. Seasonality The earth is tilted on its axis at an angle of
approximately 23.5°. As the earth revolves around the sun, tilt and
latitude determine seasons.
Solstices and Equinoxes are named for the season in the northern hemisphere.
Month Earth’s tilt Latitude where Hours of daylight
relative to the sun is
the sun directly
overhead (90°
angle of
incidence)
Summer
Solstice June Northern 23.5 Degrees
Hemisphere North 24 Hours of light near
towards the Tropic of the North Pole
sun Cancer
Most hours of daylight
in Northern
Hemisphere
24 Hours of dark near
the South Poles
Shorter days in the
Southern Hemisphere
Days lengths begins
shortening, continues
until Winter Solstice
