During the 1960s, alternating patterns of magnetic properties were discovered in rocks found on the seafloor.
Similar patterns were discovered on either side of mid-oceanic ridges found near the center of the oceanic basins.
Dating of the rocks indicated that as one moved away from the ridge, the rocks became older, and suggested that new crust was being created at volcanic rift zones.
The lithosphere is the solid, outer part of the Earth and is broken into huge sections called plates, which are slowly moving.
Subduction zones: These are areas on Earth where two tectonic plates meet and move toward each other, with one sliding underneath the other and moving down into the mantle.
Convergent Boundaries: These occur where two plates %%slide toward each other%%.
Divergent Boundaries: These occur when two plates %%slide apart from each other%%.
Transform boundaries: These occur where plates %%slide past each other in opposite directions%%.
Soils: These are a thin layer on top of most of Earth’s land surface.
Soils are composed of three main ingredients:
Soil Profile
Soils develop in response to the following factors:
Igneous Rocks: These are formed by %%cooling and classified by their silica content%%.
Metamorphic Rocks: These are formed by %%intense heat and pressure, high quartz content%%.
Sedimentary: These are formed by the %%piling and cementing of various materials%% over time in low-lying areas.
Aeration: Refers to how well a soil is able to absorb oxygen, water, and nutrients.
Degree of Soil Compaction: It is measured by dry unit weight and depends on the water content and compaction effort.
Nutrient-Holding Capacity: The ability of soil to absorb and retain nutrients so they will be available to the roots of plants.
Permeability: The measure of the capacity of the soil to allow water and oxygen to pass through it.
pH: It is the measure of how acidic or basic soil is.
Pore Size: Describes the space between soil particles.
Size of soil and particles: It determines the amount of moisture, nutrients, and oxygen that the soil can hold along with the capacity for water to infiltrate.
Water holding capacity: It is controlled primarily by the soil texture and the soil organic matter content.
Soil Food Web: It is the community of organisms living all or part of their lives in the soil, and it describes a complex living system in the soil and how it interacts with the environments, plants, and animals.
Atmospheric carbon dioxide (CO2) produced by volcanoes and methane (CH4) produced by early microbes, both greenhouse gases, likely %%produced a strong greenhouse effect and allowed the earliest life forms to develop%%.
Great Oxidation Event (GOE) 2.5 billion years ago killed almost all life on Earth.
As oxygen began to accumulate in the atmosphere, it is believed that there were two major consequences:
Troposphere: The lowest portion of Earth’s atmosphere, 0–6 miles (0–10 km) above Earth’s surface.
Stratosphere: It is located 6–30 miles (10–50 km) above Earth’s surface.
Air Mass: A large body of air that has similar temperature and moisture content.
Albedo: An expression of the ability of surfaces to reflect sunlight.
Altitude: The distance above sea level.
Carbon Cycle: The process in which carbon atoms continually travel from the atmosphere to the Earth and then back into the atmosphere.
Distance to Oceans: Oceans are thermally more stable than landmasses; the specific heat of water is five times greater than that of air.
Fronts: When two different air masses meet, the boundary between them forms a “front.”
Greenhouse Effect: %%Without this effect, Earth would be cold and inhospitable.%%
Heat: Climate is influenced by how heat energy is exchanged between air over the oceans and the air over land.
Human Activity and Climate: Climate can also be influenced by human activity.
Latitude and Location
Moisture Content of Air: It is a primary determinant of plant growth and distribution and is a major determinant of biome type.
Pollution: Greenhouse gases are emitted from both natural sources and anthropogenic sources.
Rotation: Daily temperature cycles are primarily influenced by Earth’s rotation on its axis.
Volcanoes
Land Breeze: It occurs during relatively calm, %%clear nights when the land cools down faster than the sea%%, resulting in the air above the land becoming denser than the air over the sea.
Sea Breeze: It occurs during relatively calm, %%sunny days, the land warms up faster than the sea%%, causing the air above it to become less dense.
Air closer to Earth's surface is warmer and rises due to Earth's rotation on its axis, revolution around the sun, and tilt.
High-pressure weather systems: They have higher pressure at their center than around them, so winds blow away from them.
Trade Winds: These are the prevailing pattern of easterly surface winds found in the tropics near Earth’s equator, within the troposphere or lower portion of Earth’s atmosphere.
Wind Speed: It is determined by pressure differences between air masses.
Wind Direction: It is based on the direction from which wind originated.
Coriolis Effect: A phenomenon wherein earth’s rotation on its axis %%causes winds to not travel straight%%, which causes prevailing winds in the Northern Hemisphere to %%spiral clockwise out from high-pressure areas and spiral counterclockwise toward low-pressure areas%%.
Polar cells originate as icy-cold, dry, dense air that descends from the troposphere to the ground.
This air meets with the warm tropical air from the mid-latitudes and then returns to the poles, cooling and then sinking.
Sinking air suppresses precipitation. As a result, the polar regions are deserts.
Very little water exists in this area because it is tied up in the frozen state as ice.
The amount of snowfall per year is relatively small.
Polar Vortex: A low-pressure zone embedded in a large mass of very cold air that lies atop both poles.
The bases of the two polar vortices are located in the middle and upper troposphere and extend into the stratosphere.
Due to the equator-pole temperature difference, these cold, low-pressure areas strengthen in winter and weaken in summer.
There is also a relationship between the chemistry of the Antarctic polar vortex and severe ozone depletion.
Hurricanes, cyclones, and typhoons are all the same weather phenomenon.
Hurricanes begin over warm oceans in areas where the trade winds converge.
Hurricane development requires %%tropical ocean thunderstorms and cyclonic circulation that starts to rotate them%%.
In the center of the hurricane is the eye, an area of descending air and low pressure.
Storm Surge: A rise in sea level that occurs during tropical cyclones, typhoons, or hurricanes.
Tornadoes | Hurricanes |
---|---|
Diameters of hundreds of meters | Diameters of hundreds of km |
Produced from a single convective storm | Composed of many convective storms |
Occur primarily over land | Occur primarily over oceans |
Require substantial vertical shear of the horizontal winds | Require very low values of vertical shear in order to form and grow |
Typically last less than an hour | Last for days |
Monsoons: These are strong, often %%violent winds that change direction with the season%%.
Monsoon winds: These blow from cold to warm regions because cold air takes up more space than warm air.
Monsoons blow from the land toward the sea in winter and from the sea toward land in the summer.
Watershed: A land area that drains rainfall and snowmelt into a lake, ocean, or aquifer.
Mississippi River watershed: The largest watershed in the United States, which drains more than one million square miles or land.
Watershed management: It reduces pesticides and fertilizers that wash off farm fields and into nearby waterbodies by using land, forest, and water resources in ways that don't harm plants and animals.
The amount of heat energy received at any location on Earth is a %%direct effect of the angle of the sunlight reaching the Earth’s surface%%.
The angle at which sunlight strikes Earth v%%aries by location, time of day, and season due to Earth’s orbit around the sun and its rotation around its tilted axis%%.
Seasonal changes in the angle of sunlight are caused by the tilt of Earth’s axis, which is the basic mechanism that %%results in warmer weather in summer than in winter%%.
Sunlight shining on Earth at a lower angle %%spreads its energy over a larger area, making it weaker than if the sun were higher overhead%%.
%%Climates become cooler and the cold season lasts longer as elevation increases%%.
%%Higher elevations have lower air pressure%% due in part to there being fewer atoms and molecules per unit of air and, thus, cooler temperatures.
Many high-altitude plains are technically deserts because they are on the downwind (leeward) side of a mountain range or continental mass.
Latitude: A measure of distance either north or south from the equator.
Tropic of Cancer: The northernmost latitude reached by the overhead sun.
Tropic of Capricorn: The southernmost latitude reached by the overhead sun.
Mountain ranges: These are barriers to the smooth movement of air currents across continents.
The mountain range's leeward side is drier than the windward side because air on this side has less moisture.
During normal conditions, easterly trade winds move water and air toward the west.
The trade winds, in piling up water in the western Pacific, make a deep warm layer in the west that pushes the thermocline down while it rises in the east.
Air pressure patterns reverse direction, causing trade winds to decrease in strength.
This causes the normal flow of water away from western South America to decrease “pile up.”
As a result, the thermocline off western South America becomes deeper and there is a decrease in the upwelling of nutrients, which causes extensive fish kills.
A band of warmer-than-average ocean water temperatures develops off the Pacific coast of South America.
Effects are strongest during the Northern Hemisphere winter because ocean temperatures worldwide are at their warmest.
Increased ocean warmth enhances convection, which then alters the jet stream
Trade winds that blow west across the tropical Pacific are stronger than normal.
This then results in an increase in the upwelling off of South America.
This then results in cooler-than-normal sea surface temperatures off of South America.
This then results in wetter-than-normal conditions across the Pacific Northwest, and both drier- and warmer-than-normal conditions in the southern United States.
This then results in an increase in the number of hurricanes.
The southeastern US has warmer winters and the northwest cooler ones, while India and southeast Asia have heavier monsoons.
Warmer or cooler ocean temperatures
Increase or decrease in the amount of normal rainfall
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