Ch. 3 Key Terms

Question 1

geosphere

Answer 1

The solid part of Earth that consists of all rock, as well as the soils and loose rocks on Earth’s surface

Question 2

hydrosphere

Answer 2

all of the water on or near Earth’s surface.

Question 3

crust

Answer 3

composed almost entirely of light elements. The crust makes up less than 1 percent of Earth’s mass.The crust is Earth’s thinnest layer.

Question 4

mantle

Answer 4

the layer beneath the crust, makes up 68 percent of the mass of Earth. The mantle is approximately 2,900 km thick and is made of rocks of medium density.

Question 5

core

Answer 5

Earth’s innermost layer is the core. The core, which has a radius of approximately 3,400 km, is composed of the elements having the greatest density.

Question 6

lithosphere

Answer 6

Earth’s outer layer is the lithosphere. It is a cool, rigid layer, 15 km to 300 km thick, that includes the crust and uppermost part of the mantle.

Question 7

asthenosphere

Answer 7

the layer beneath the lithosphere. The asthenosphere is a pliable, solid layer of the mantle made of rock that flows very slowly and allows tectonic plates to move on top of it.

Question 8

tectonic plate

Answer 8

The lithosphere is divided into pieces called tectonic plates that glide across the underlying asthenosphere in much the same way a chunk of ice drifts across a pond. The continents are located on the tectonic plates and slowly, over eons, move around with them. The major plates include the Pacific, North American, South American, African, Eurasian, andAntarctic plates.

Question 9

chemical warning

Answer 9

wears down rocks, making them smoother as time passes

Question 10

erosion

Answer 10

transports the materials elsewhere

Question 11

atmosphere

Answer 11

Earth is surrounded by a mixture of gases known as the atmosphere. Nitrogen, oxygen, carbon dioxide, and other gases are all parts of this mixture. Earth’s atmosphere changes constantly as these gases are added and removed.

Question 12

troposphere

Answer 12

The atmospheric layer nearest Earth’s surface is the troposphere. The troposphere extends to about 18 km above Earth’s surface. Almost all of the weather occurs in this layer. The troposphere is Earth’s densest atmospheric layer.

Question 13

stratosphere

Answer 13

Above the troposphere is the stratosphere. The stratosphere, separated from the troposphere by the tropopause, shown in Figure 2.3, extends from about 18 km to an altitude of about 50 km. Temperatures rise as altitude increases because ozone in the stratosphere absorbs the sun’s ultraviolet(UV) energy and warms the air.

Question 14

ozone

Answer 14

O3, is a molecule made up of three oxygen atoms. Almost all the ozone in the atmosphere is concentrated in the ozone layer in the stratosphere. Ozone reduces the amount of harmful UV radiation that reaches Earth.

Question 15

radiation

Answer 15

the transfer of energy as electromagnetic waves. When you stand before a fire or a bed of coals, the warmth you feel has reached you by radiation.

Question 16

conduction

Answer 16

is the transfer of energy in the form of heat from a warmer object to a colder object when the objects are placed indirect physical contact.

Question 17

convection

Answer 17

is the transfer of energy that takes place when variations in temperature move the matter making up air.

Question 18

greenhouse effect

Answer 18

the trapping of the sun’s warmth in a planet’s lower atmosphere, due to the greater transparency of the atmosphere to visible radiation from the sun than to infrared radiation emitted from the planet’s surface.

Question 19

water cycle

Answer 19

The continuous movement of water into the air, onto land, and then back to water sources

Question 20

evaporation

Answer 20

the process by which liquid water is heated by the sun and then rises into the atmosphere as water vapor.

Question 21

condensation

Answer 21

water vapor forms water droplets on dust particles

Question 22

precipitation

Answer 22

water droplets form clouds, in which the droplets collide, stick together, and create larger, heavier droplets.These larger droplets fall from clouds as rain in a process called precipitation

Question 23

salinity

Answer 23

The salinity of ocean water is the concentration of all the dissolved salts it contains. The average salt content of ocean water is 3.5 percent by weight

Question 24

fresh water

Answer 24

Most of the water on Earth is salt water in the ocean. A little more than3 percent of all the water on Earth is fresh water

Question 25

biosphere

Answer 25

he narrow layer aroundEarth’s surface in which life can exist. The biosphere is made up of the uppermost part of the geosphere, most of the hydrosphere, and the lower part of the atmosphere.