Unit 4 Earth Systems and Resources [4.1-4.7]

unequal heating of Earth's surface

1) The sun's rays strike the earth more directly at the equator. The rays are spread out over more surface area at higher latitudes.

2) The sun's rays pass through more atmosphere at higher latitudes due to the curvature of the earth.

insolation

incoming solar radiation (sunlight) to earth; depends on the latitude and season

Seasons

Caused by the tilt of Earth on its axis as it revolves around the Sun. Winter in a hemisphere happens when it tilts away from the sun, and summer when it tilts towards the sun.

Latitude

Distance north or south of the equator; higher latitudes = further away from the equator (0) and closer to the poles (90)

Solar intensity

The amount of solar energy striking a given location on earth. Higher intensity = more incoming energy from the sun

Equator

An imaginary circle at 0 degrees latitude, halfway between the North Pole and the South Pole; where the suns rays strike earth most directly

Earth's axis of rotation

tilted 23.5 degrees with respect to the sun. This causes earth's seasons, as the northern hemisphere tilts towards the sun (summer) and away from the sun (winter), while it orbits.

Solstice

The two days of the year when one hemisphere is maximally tilted towards the sun and the other is maximally tilted away. Summer solstice = longest day of the year, winter solstice = shortest day of the year.

Equinox

The two days of the year on which neither hemisphere is tilted toward or away from the sun. Both hemisphere's experience almost exactly 12 hours of day and 12 hours of night (equal <-> equinox)

infrared radiation

Electromagnetic waves given off from earth's surface as heat when sunlight strikes it. Trapped by greenhouse gases in the atmosphere, heating earth.

atmosphere

The mixture of gases that surrounds earth. Broken into 5 distinct layers.

Troposphere

The lowest layer of Earth's atmosphere; where most of earth's weather occurs

Stratosphere

The second-lowest layer of Earth's atmosphere. Contains beneficial ozone (O3) molecules that block UV radiation.

Mesosphere

The 3rd layer of Earth's atmosphere; immediately above the stratosphere

Thermosphere

The outermost layer of Earth's atmosphere. It is by far the thickest layer of earth's atmosphere. It blocks harmful X-ray and UV radiation, and the northern lights (aurora borealis) occur in this region

Exosphere

The outer layer of the thermosphere, extending outward into space.

Hadley Cell

Convection Currents that cycle between the equator, 30 degrees North and South. Warm air at equator rises, cools & expands, rains, spreads out, and then sinks back down to earth @ 30 degrees North & South

Coriolis effect

The effect of Earth's rotation on the direction of winds and ocean currents. Deflects winds to the left between 0 and 30 degrees; to the right between 30 and 60 degrees

Air Property: Moisture

Warm air holds more moisture than cold air

Air Property: Density

Warm air is less dense than cold air, so it rises

Air Property: Pressure

As air rises, it is under less atmospheric pressure, so it expands and cools

soil

A loose mixture of rock fragments, organic material, water, and air that can support the growth of vegetation. NOT DIRT!

parent material

the base, rock material that was weathered and then eroded to produce the soil in a given area. (the underlying rock that became the soil)

Weathering

The breaking down of rocks and other materials on the Earth's surface by physical (wind, rain, plants roots) and chemical processes (lichen secreting acid)

Erosion

The physical movement of rock fragments and sediment from an ecosystem.

Weathering vs. Erosion

Weathering = wind, rain, acids breaking rocks into smaller pieces.

Erosion = those smaller pieces being carried away by wind & rain

Deposited

The act of sediments and rock fragments being placed somewhere new by the process of erosion.

Ex: the strong winds deposited the soil that was blown off the mountain into a nearby valley.

Soil horizons

Layers of soil

O layer

the uppermost horizon of soil. It is primarily made up of organic material, including waste from organisms, the bodies of decomposing organisms, and live organisms - especially decomposers like earthworms and beetles.

A horizon (topsoil)

The first layer of actual soil. It's nutrient-rich because it is a mixture of mineral material and organic material from the O layer.

B horizon (subsoil)

The second layer of soil. Found underneath the topsoil. Mostly minerals with very little organic matter.

C horizon (parent material)

The least weathered horizon. Still very similar to the underlying parent material since it has undergone very little weathering.

soil texture

The percentage of a given soil that is made up of sand, silt, and clay.

particle size

The relative sizes of sand, silt, and clay. Sand is the biggest, then silt, then clay.

Soil property: pH

The acidity of a given soil. Lower (more acidic) soil pH can leach nutrients out of the soil, and make metal ions such as aluminum more soluble, damaging plant roots.

Soil property: salinity

The salt content of soil. High salt concentration can result from over irrigation with ground water and can be toxic to plants.

Soil property: porosity

How much empty space there is in a given soil. In other words, how tightly does the soil pack together.

Sand packs very loosely and has high porosity. Clay packs very tightly and has low porosity.

Soil property: permeability

Directly related to soil porosity; how easily water can drain through a soil.

More porous = more permeable = easier for water to drain through.

Water holding capacity

A measure of how much water a given soil can hold. Sandy soils don't hold water as well as soils with more clay. A dense O layer also helps soil retain water, losing less to evaporation.

Loam

a balanced mixture of 40% sand, 40% silt, and 20% clay that is ideal for plant growth

soil fertility

Soil's ability to support plant growth. Primarily dependent on the soil's ability to hold nutrients (N, P, K) and water needed for plants.

geological

concerned with geology, the science that deals with the physical nature of the earth

convergent boundary

A plate boundary where two plates move toward each other; primarily result in creation of mountain ranges, and sometimes volcanoes and earthquakes.

divergent boundary

A plate boundary where two plates move away from each other; primarily results in seafloor spreading, rift valleys, and sometimes volcanoes and earthquakes

transform boundary

A plate boundary where two plates move past each other in opposite directions; primarily results in earthquakes

earthquake

The shaking that results from tectonic plates slipping past one another. The stress of the plates pulling on each other overcomes the locked fault, releasing stored energy.

Island arcs

a curved chain of volcanic islands that form where a tectonic plate moves over a geologic hotspot

Hotspot

A weak spot in the middle of a tectonic plate where magma rises to the surface of the lithosphere; forms a volcano (ex: Hawaii & Yellowstone)

seafloor spreading

The process that creates new lithosphere on the sea floor as plates move away from each other at the mid-ocean ridges. Magma rises and cools, leading to formation of new sea floor

rift valley

A deep valley that forms where two plates move apart

tectonic plates

Large movable rock plates of lithosphere that float on top of the magma of the earth's mantle.

fault

A break in the earth's crust where there is plate movement on either side

convection currents

Circular currents in the mantle caused by the magma being heated by earth's core. Hot magma rises towards earth's surface, cools and spreads out along the lithosphere, and then sinks back down towards the core.

Mountains

Formed by two continental plates colliding and forcing each other upwards.