Earth Science Unit #3

What were the 3 purposes of dam building in the 20th century?

1. the giant concrete walls tame big, wild rivers

2. provides steady water supplies

3. control floods generate electricity

What part of the government sought to dam the US rivers to harness their power and create water resoirs for communities? How many dams did they build?

the Bureau of Reclamation, 84,000 dams

What is the most widely used “green” energy source in the world? How much more power does it produce?

water power, 8x

What is it called when water moves in and around the earth system, changing from one physical state to another?

the water cycle

What is the volume of water that passes through each cycle annually?

water balance

How do streams form?

melting snow and rain run of slopes become a source of freshwater which will flow into depressions and carves out small channels

What can be a source or destination of many streams?

lakes

what is the length of time that a given volume of water remains in streams? How long is it?

residence time, 14 days

how much more water is stored in ground water than in streams or lakes?

70x

how much more freshwater is stored in ice than in groundwater?

3x

What are the 5 things that determine the amount of water that remains on the surface as runoff?

1. intensity and duration of rainfall

2. amount of water already in the soil

3. nature of the surface material

4. slope of the land

5. extent and type of vegetation

What is an area of land drained by a stream. (also known as a watershed)

drainage basin

What separates drainage basins? where are they found?

drainage divides, and found along the hgih ground separating drainage basins

how much of earth’s land surface contains rivers that eventually drain to the ocean?

2/3

What is base level of a river?

the lowest point to which a stream can flow

What is the ultimate base level?

the ocean

What 2 things determines the amount of water in a stream channel?

the size of the area it drains and the average precipitation over that area

What are the 4 types of drainage patterns?

dendritic, rectangular, radial, and trellis

What is the drainage pattern that have characteristics of areas where the geology is relatively uniform?

dendritic

What drainage pattern is associated with horizontal rock layers?

dendritic

What drainage pattern is treelike?

dendritic

What drainage pattern has streams interesting at characteristic V pattern? (tip of V points which way?

dendritic, downstream

What drainage pattern develops in areas of folded layers of weak and resistant rocks?

trellis

What drainage pattern occupies in valleys flowing parallel to ridges?

trellis

What 2 drainage patterns do streams intersect at right angles?

trellis and rectangular

What drainage pattern occurs in regions where the streams are controlled by joints and fractures in underlying bedrock?

rectangular

What drainage pattern has water that flows on ridges?

trellis

What drainage pattern are typically found on volcanoes where streams flow directly downhill in all directions, away from the summit?

radial

what are scientists who study water?

hydrologists

What is the slope of a stream (change in elevation of a stream over a horizontal distance)?

stream gradient

Where is the stream gradient the steepest?

the headwater

The steeper the gradient of a stream, the ________ the velocity?

higher

What is it called when there are boulders and other debris is the stream? What does it do to the velocity?

channel roughness, lowers it

what is length of the surface of the channel banks and bed in contact with the water?

wetted perimeter

A larger wetted perimeter creates what which does what to the velocity of the stream?

produces drag, lowering velocity

The larger the stream discharge, what can be said about the effect of frictional drag from wetted perimeter?

the less significant the effect

What is the volume of water that passes a given point in one second?

stream discharge

How can you calculate stream discharge?

cross sectional area (A) multiplied by the average channel velocity (V)

What is the wear away of beds and banks?

erosion

What is larger sand and gravel particles that bounce/roll along the streambed?

bed load

What are finer particles that are carried in suspended water columns?

Suspended load

What are materials usually invisible in the stream?

dissolved load

What river in the US has the largest amount of water discharged by mouth?

Mississippi river

Deposits can cause the main channel to split into small channels called what?

braided streams

What are broad flat lands alongside the stream channel?

flood plains

Velocity is the ________ along the banks and bed of the stream? Is friction high or low?

lowest, high

Velocity is the ________ in the center of the stream? Is friction high or low?

highest, low

lower elevations of most streams have what? and are called meanders or what?

numerous broad curves, lateral migration

what is a temporary overflow of a river onto adjacent lands not normally covered by water?

flood

What is the most common geological hazard?

flood

What is the most common cause of floods?

precipitation

What are the 3 ways to control floods?

levees (flood walls), floodways (diversion channels), and dams

Where does drinking water come from?

streams and lakes on Earth’s surface or from groundwater

What is water that is present in rocks or unconsolidated material below earth’s surface?

groundwater

What is groundwater that dissolves away rock
(ex. limestone) that it passes over/through?

mineral water

what ppm (parts per million) does water have to be to be considered mineral water?

at least 250ppm

What is usually tap water that went through another round of water treatment? What ppm does it have to have?

purified water, less than 10 ppm

How much more water is below ground than in lakes and streams on Earth’s surface?

about 70x more

How is most groundwater found?

in billions of tiny spaces between mineral grains or in narrow cracks

What is the measure of the proportion of a material that is made up of spaces?

porosity

What is the capacity of water to flow through earth materials?

permability

What are the conditions for an area to be considered a wetland?

the area must be saturated with water and have poorly drained soils and specific types of plants

What two things redistribute Earth’s heat and play a crucial role in controlling our planet’s climate?

Oceanic and atmospheric circulation patterns

What consists of the air around us and serves as a protective
layer against the many potential hazards from space?

atmosphere

The interaction of the thin layer of what with what determines the distribution of global temperatures?

air and solar radiation

What supples the energy necessary for cloud formation, precipitation, and wind generation?

solar radiation

What is the specific mix of gases in Earth’s
atmosphere?

air

What two gases make up 99% of dry air?

nitrogen and oxygen

What is range in the amount of water vapor in the air?

0% dry climate -7% humid climates

Early atmospheres originated from what?

gases expelled from extensive volcanism and
comets and meteorites that collided with Earth

About 4 billion years ago, what gas was absent from earth’s surface and what other gas made up about ¼ of all gases?

oxygen, carbon dioxide

How did the oceans form?

As Earth cooled, water vapor condensed to form a nearly continuous rain that eventually collected in oceans

About 4 million years ago, what did the rain do to carbon dioxide?

stripped it from the atmosphere

Carbon dioxide and water in the presence of sunlight produced what about 4 million years ago?

organic matter and oxygen

how long did it take before free oxygen began to accumulate in the atmosphere, then continued increasing?

2 billion years

Almost all atmospheric gases (99%) lie within how many miles of Earth’s surface?

20

½ of the atmosphere is how many miles below earth’s surface?

3.5

How far does the atmosphere go up?

6,214 miles

As you travel upward from the Earth’s surface what happens to the density?

it rapidly decreases

The higher the kinetic energy, what happens to the atomic motion?

it increases

What is the total kinetic energy of all of the atoms in a substance?

heat

what is the average kinetic energy of all of the atoms in a substance?

temperature

What is the amount of heat it must absorb (or
release) to produce a corresponding temperature increase
of decrease?

heat capacity

What are the 5 layers of the atmosphere? in order starting with the lowest layer

troposphere, stratosphere, mesosphere, thermosphere, exosphere

What is the lowest layer of the atmosphere?

troposphere

What layer of the atmosphere contains our weather system, air pollution, etc.?

troposphere

What layer of the atmosphere contains 75%-80% of the atmosphere?

troposphere

What layer of the atmosphere is the 2nd layer?

stratosphere

What layer of the atmosphere is where objects will burn up?

mesosphere

What layer of the atmosphere is the outermost layer?

thermosphere

What layer of the atmosphere blocks much of the harmful cosmic radiation?

thermosphere

What layer of the atmosphere contains auroras and space stations?

thermosphere

About how much solar radiation is absorbed at the earth’s surface?

50%

Electromagnetic Radiation (EMR) can be __________, ____________, or ____________.

scattered, reflected, or absorbed

What is the heating of the atmosphere known as?

the greenhouse effect

What is the amount of moisture in the air?

humidity

What is the pressure exerted by the weight of an overlying column of air?

atmospheric pressure

What does air density measure?

the mass of atoms and molecules (gases) per volume of air

When air is cooled what does it do? resulting in what?

contracts, smaller volume of gas molecules

What happens to the density of when air contracts?

increase in density and generate higher pressures