Transcript Earth Science - Tuslaw Local School District

Earth Science
8th Grade OAT
Review
7th 1. Explain the Biogeochemical cycles which move
materials between the lithosphere (land), hydrosphere
(water) and atmosphere (air)
 A. Water is always moving between the atmosphere and Earth’s
surface
 B. Water can contain minerals, pollutants, and other agents
depending on the land, runoff and chemicals in the air
 C. The movement of water between the atmosphere and
Earth’s surface is called the water cycle
 Water vapor enters the air by evaporation from the oceans and other
bodies of water
 Water vapor is also added to the air by living things - this process is
called transpiration
 Some of the water vapor the atmosphere condenses to form clouds - this
is called condensation
 Rain and other forms of precipitation fall from the clouds toward the
surface
 The water then runs off the surface, or moves through the ground, back
into the oceans lakes and streams
7th 2. Explain the Earth’s capacity to absorb and recycle
materials naturally (e.g. smoke, smog, sewage) can
change the environmental quality depending on the
length of time involved (e.g. global warming)
 A. Most changes in the world climate are caused by natural factors. In the
last 100 years, however, human activities have also had an effect on Earth’s
climate and atmosphere
 B. Pollution (smog, smoke, sewage, increased carbon dioxide, etc.) and
can produce harmful, possibly long term effects to the Earth.
 C. Two of the most important worldwide issues are global warming and
thinning of the atmosphere
 Greenhouse effects is essential to the extent that it is a natural process
that keeps Earth’s atmosphere at a temperature that is comfortable for
most living things
 Gases that trap solar energy are called greenhouse gases - water vapor,
carbon dioxide, methane
 Human activities that add greenhouse gases to the atmosphere may be
warming Earth’s atmosphere (burning wood, coal, oil and natural gas)
 Increased carbon dioxide traps more heat, the result is global warming
7th 2. Continued
 D. Ozone in the stratosphere filters out much of
the harmful ultraviolet radiation from the sun.
 Chemicals produced by humans have been damaging
the ozone layer
The main cause of ozone depletion is a group of
compounds called chlorofluorocarbons (CFC’s)
 CFC’s are found in spray cans, refrigerators, and air
conditioners and can last for years in the atmosphere
and can rise all the way to the stratosphere
 CFC’s are broken down by the ultraviolet radiation in the
stratosphere forming chlorine. The chlorine atoms
break the ozone into oxygen atoms

7th Earth 3. Describe the water cycle and explain
the transfer of energy between the atmosphere and
the hydrosphere
A. The movement of water between the atmosphere and the Earth’s
surface is called the water cycle
 Water vapor enters the air by evaporation from the oceans and other
bodies of water
 Water vapor is also added to the air b living things - this process is
called transpiration
 Some of the water vapor the atmosphere condenses to form a cloud this process is called condensation
 Rain and other forms of precipitation fall from the clouds toward the
surface
 The water then runs off the surface, or moves through the ground,
back into the ocean, lakes and streams
 Evaporation uses energy (sunlight and heat)
 Condensation releases energy (thunderstorms/ hurricanes)
B. Energy can not be created or destroyed, it is just transferred from one
form to another
C. Energy from the sun drives the water cycle
7th Earth 4. Analyze data on the availability of fresh
water that is essential for life and for most industrial and
agricultural processes. Describe how rivers lakes and
ground water can be depleted or polluted becoming less
hospitable to life and even becoming unavailable or
unsuitable for life
 A. Most of the Earth’s water - more than 97% is salt water, only 3% is fresh
water
 3/4 of the 3% of fresh water is found in ice masses at the North and
South Pole
 Less than 1% of the water on Earth is fresh water available for humans
to use. Usable fresh water is only found in lakes and rivers and shallow
ground water (aquifers)
 B. Water is used for most agricultural processes and in industry
 On the farms a constant supply of fresh water is essential
 Some parts of the U.S. do not receive enough annual rainfall to produce
crops therefore irrigation is used
 Water is a major component used in the manufacturing of most products
in your classroom (e.g., paper, and textbooks)
 Industries also use water to cool machinery (e.g., power plants and
7th Earth 4. Continued
 C. Water Pollution is the addition of any substance
that has a negative effect on water or living things
that depend on water
 Major sources of water pollution are human wastes,
industrial wastes, agricultural chemicals and wastes, runoff
from roads
 Many kinds of water pollution are so difficult to clean up,
the most important place to stop pollution is at the source
 Ground water is difficult to clean - pollution can cling to
rock particles of the aquifer
 D. Droughts and overuse can deplete ground water
 It takes a long time for surface water to percolate through
the ground and replace the water that was used
7th Earth 5. Make simple weather
predictions based on the changing cloud
types associated with frontal systems
 A. Meteorologists classify clouds into three man types
 Cumulus - looks like fluffy rounded piles of cotton
 Usually indicate fair weather
 Towering cumulus clouds with flat tops, cumulonimbus (usually form
at cold fronts), often produce thunderstorms
 Stratus - form in flat layers
 Cover all or most of the sky
 As they thicken may produce drizzle, rain, or snow (nimbostratus)
 Cirrus - wispy, feathery clouds
 Only form at high levels where temps. Are very low
 Mostly made of ice crystals
 Often predict precipitation within 24 hours
 Usually form at the leading edge of warm fronts
 Darker clouds contain more moisture
 B. Clouds that form near the ground are known as fog
7th Earth 5. Continued
 C. front - four types
 Cold Front - boundary between a cold air mass and a warm
air mass
 Brings brief storms and cooler weather
 Warm Front - boundary between a warm air mass and a
cold air mass
 Usually accompanied by precipitation
 Stationary Front - boundary between a warm air mass and
cold air mass when no movement occurs
 Brings long periods of precipitation
 Occluded Front - boundary on which a warm front has been
overtaken by a cold front
 Brings precipitation
7th Earth 6. Determine how weather observations and
measurements are combined to produce weather maps
and that data for a specific location at one point in time
can be displayed in a station model
 A. A weather map is a snap shot of
conditions over a large area for a
particular time period
 Data is collected from weather stations all
over a large area for a particular time
period
 Local weather maps provide data for a
specific locations and elements of weather
7th Earth 7. Read a weather map to
interpret local, regional, and national
weather
 A. A weather map is a snap shot of conditions over a
large area for a particular time period
 B. On some weather maps you see curved lines
 Lines that connect places on the map that have the same air
pressure are called isobars
 Air pressure readings are given in inches of mercury, or in
millibars, or both
 Isotherms are lines joining places that have the same
temperature
 These are labeled with temperature in degrees Fahrenheit,
degrees Celcius, or both
 C. Standard symbols on weather maps show fronts, areas of
high and low pressure, types of precipitation, wind speed, wind
direction, cloud cover, and temperatures
7th Earth 8. Describe how temperature and
precipitation determine climatic zones (biomes)
(e.g. desert, grassland, forest, tundra, alpine)
 A. Climate zones are geographic areas that cover major parts of the
earth and share similar climates (temperature and precipitation)
 B. The major terrestrial (land) biomes are desert, grassland, forests, tundra
and apline
 Not all scientists agree on the number and names of the biomes
 Desert -receive less than 25cm of rainfall per year
 The amount of evaporation is greater than the precipitation
 Temperature in the desert varies depending on the time of day
 Some deserts experience freezing temperatures in the winter
 Grasslands - receive between 25cm to 75cm of rainfal annually
 This is more rainfall than a desert but still not enough for many
trees to grow
 A savanna is a grassland located close to the equator that receives
as much as 120cm of rainfall annually

7th
Earth
8.
Continued
Forests - three kinds of forest biomes include rain forest, deciduous, and
coniferous
 Rain forests
 Tropical rain forest - receives 212cm of rainfall annually
 Warm temperatures do not vary and sunlight is fairly constant
 Temperate rain forest - receives over 300cm of rainfall per
annually
 Temperature is moderate to cool
 Deciduous forest - receive at least 50cm of rainfall annually
 Temperatures vary (spring, summer, fall, winter)
 Coniferous forest - receive large amounts of snowfall
 Colder climate - winters are very cold
 Tundra - receives 25cm or less of rain or snow annually
 Receives the least amount of sunlight of any of the biomes
 Alpine - include mountain ranges and land that is covered with thick sheets
of ice
Very cold temperatures,
7th Earth 9. Describe the connection between
the water cycle and weather related phenomenon
(e.g. tornadoes, droughts, floods, hurricanes)
 A. A storm (e.g. tornadoes, hurricanes) is a violent disturbance
in the atmosphere that can disrupt the water cycle
 A tornado forms in a cumulonimbus cloud (same cloud as
thunderstorms)
 Occurs in spring in summer due to the humid
(evaporation) warm air masses coming from the south
 A hurricane receives energy from warm humid air at the
ocean surface
 As air rises it forms clouds and thus more air is drawn
into the system
 Inside the storm are bands of heavy rains
 B. Long period of unusually low precipitation are known as a
drought
7th Earth 9. Continued
 C. Floods occur when so much water
pours into a stream or river that it
overflows its banks and covers the land
on either side of the channel
 Flash flood is a sudden, violent flood that
occurs within a few hours, or even minutes
of a storm