You have previously covered the earths atmosphere, but this section is dedicated to the earths surface and what happens in relation to the atmosphere. The earths atmosphere has a very big influence on the surface of the earth with its pressure differences and many other factors. This is the region of the earth where everything is directly impacted onto the living realm of the world.
Water cycle
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Water is a chemical substance that is the driving force of earths organisms. Without water, no organism would absolutely no organisms. But humans being the largest group of organism can only consume freshwater which is only 3% of the water on earth. Considering the earths size, 3% is a significant amount but even due to the rapid population increase, fresh water is becoming a scarcity. Water is what keeps everything alive, no matter what you are.
Water can be seen throughout the globe because it covers 70% of the earths surface. But water do not stay in one place, and are constantly changing form. Water can become liquid, solids, and gas due to many reasons. One of the biggest circulation of water can do is through the water cycle.
Water cycle is the process water circuiting through the earths surface, to the atmosphere and back down. The water cycle has three steps of which are Evaporation, Condensation, and precipitation. In each of the process, water changes its form from, gas, solid, and liquid.
Evaporation- When the suns radiation heats and radiates the surface of the earth, they heat the water on the surface. When water is heated it becomes less dense and changes into gas which cannot be seen with the naked eyes. The gas then rises towards the atmosphere and transitions into the next process which is condensation.
Condensation- When the the water vapour (water gas) reaches a certain altitude, the water cools down because of the low temperatures and this results in the condensation of water. In other words, the water vapour starts becoming dense or starts to changes its form to liquid. Because water molecules need a base for staying in the atmosphere, they grab onto particles that are in the atmosphere. The water molecules then start forming ice crystals on the particles. Billions of these formation is what creates clouds. Clouds such as stratus clouds, cumulus clouds, and cirrus clouds form depending on the conditions. When the water molecules and particles become to heavy, they fall towards the surface because of gravity. The fall of water molecules in various forms (liquid or solid) is called precipitation.
Water can be seen throughout the globe because it covers 70% of the earths surface. But water do not stay in one place, and are constantly changing form. Water can become liquid, solids, and gas due to many reasons. One of the biggest circulation of water can do is through the water cycle.
Water cycle is the process water circuiting through the earths surface, to the atmosphere and back down. The water cycle has three steps of which are Evaporation, Condensation, and precipitation. In each of the process, water changes its form from, gas, solid, and liquid.
Evaporation- When the suns radiation heats and radiates the surface of the earth, they heat the water on the surface. When water is heated it becomes less dense and changes into gas which cannot be seen with the naked eyes. The gas then rises towards the atmosphere and transitions into the next process which is condensation.
Condensation- When the the water vapour (water gas) reaches a certain altitude, the water cools down because of the low temperatures and this results in the condensation of water. In other words, the water vapour starts becoming dense or starts to changes its form to liquid. Because water molecules need a base for staying in the atmosphere, they grab onto particles that are in the atmosphere. The water molecules then start forming ice crystals on the particles. Billions of these formation is what creates clouds. Clouds such as stratus clouds, cumulus clouds, and cirrus clouds form depending on the conditions. When the water molecules and particles become to heavy, they fall towards the surface because of gravity. The fall of water molecules in various forms (liquid or solid) is called precipitation.
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Precipitation- As explained above, Precipitation is the fall of water molecules from the atmosphere due to gravity. Precipitation can come down in forms such as rain, snow, hail and sleet.
Precipitation that fall on bodies of water restarts the cycle immediately, but precipitation that fall on surface can travel through thousands of kilo meters through land until reaching a body of water. Precipitation (water) that fall on land are called runoffs. Runoffs usually travel long distances until reaching their destination, which can be oceans, lakes, or into the ground. When rain fall on mountain tops, they start flowing down due to gravity, which can be called streams. Streams are the natural channel of flowing water, and when multiple streams flow together, they create a river system. During the process of flowing down the mountain slopes, they pick up small pieces of gravel and particles, these particles hit the sides of the stream. This is called erosion, it is when rocks are worn by small particles brought down by the flow of the stream. Streams and tributaries feed the major rivers with runoff they have collected in the mountains. This entire process takes place in the region called the watershed. But what if precipitation is not water, but snow. If they do not melt as fast as they fall, they become glaciers. When layers of snow fall on another layer of snow, the pressure exerted on the bottom layer would create ice. These huge chunks of ice are one of the biggest source of fresh water. This brings us to another topic which is fresh water. Fresh water is an essential element for sustaining life, and only 3% of the water on earth is fresh, and are usually located deep underground, glaciers or lakes which form in depression on land. Even though fresh water may exist in many locations, one fourth of the earths fresh water lyes underground.
Underground water is present when there is a water table which is the layer above the saturated zone. Lakes and ponds are usually found in the water table. The saturated zone is the layer of earths soil where pores are filled with fresh water water. Even in the surface of earth there is resistance by some rocks. When water is able to pass through rocks, it is called a permeable rock, and if the rocks are saturated, they are called aquifer rocks. Aquifer rocks are one of the major suppliers of fresh water to countries. If they do not let water pass through, they are called impermeable rocks. From this explanation, we can see that the earths interior is as complicated as the outside, and there is more that lies beneath the surface than there is in the atmosphere.
Precipitation- As explained above, Precipitation is the fall of water molecules from the atmosphere due to gravity. Precipitation can come down in forms such as rain, snow, hail and sleet.
- Rain- precipitation of condense liquid water. The most common kind, can happen throughout the entire year.
- Snow- precipitation of ice crystals (slightly solid water). Commonly occur in cold period of the year
- Hail- precipitation of ice (solid water)
- Sleet - rain that contains some ice
Precipitation that fall on bodies of water restarts the cycle immediately, but precipitation that fall on surface can travel through thousands of kilo meters through land until reaching a body of water. Precipitation (water) that fall on land are called runoffs. Runoffs usually travel long distances until reaching their destination, which can be oceans, lakes, or into the ground. When rain fall on mountain tops, they start flowing down due to gravity, which can be called streams. Streams are the natural channel of flowing water, and when multiple streams flow together, they create a river system. During the process of flowing down the mountain slopes, they pick up small pieces of gravel and particles, these particles hit the sides of the stream. This is called erosion, it is when rocks are worn by small particles brought down by the flow of the stream. Streams and tributaries feed the major rivers with runoff they have collected in the mountains. This entire process takes place in the region called the watershed. But what if precipitation is not water, but snow. If they do not melt as fast as they fall, they become glaciers. When layers of snow fall on another layer of snow, the pressure exerted on the bottom layer would create ice. These huge chunks of ice are one of the biggest source of fresh water. This brings us to another topic which is fresh water. Fresh water is an essential element for sustaining life, and only 3% of the water on earth is fresh, and are usually located deep underground, glaciers or lakes which form in depression on land. Even though fresh water may exist in many locations, one fourth of the earths fresh water lyes underground.
Underground water is present when there is a water table which is the layer above the saturated zone. Lakes and ponds are usually found in the water table. The saturated zone is the layer of earths soil where pores are filled with fresh water water. Even in the surface of earth there is resistance by some rocks. When water is able to pass through rocks, it is called a permeable rock, and if the rocks are saturated, they are called aquifer rocks. Aquifer rocks are one of the major suppliers of fresh water to countries. If they do not let water pass through, they are called impermeable rocks. From this explanation, we can see that the earths interior is as complicated as the outside, and there is more that lies beneath the surface than there is in the atmosphere.
Weathering & mass movement
One of earths most interesting factor is the constant changing of its surface by many processes. These processes can include, mechanical weathering, chemical weathering, and erosion. Weathering is the process by which rocks are chemically altered or physically broken apart. But within these two categories are other forms of weathering.
Mechanical Weathering is the alternation of rocks physically, and usually needs water to take place. Mechanical weathering can happen in many ways, which includes frost wedging, abrasion, and he growth of plant roots.
Another category in which weathering can occur is chemical weathering. This is the break down of rocks by chemical reactions. Chemical weathering usually takes place in regions where water is commonly found. Water being one of the most abundant liquid on the surface can be highly reactive to some substances. Usually clouds that form in the atmosphere can rain water that can be a bit acidic. This acid rain is called carbonic acid, the combination of water and carbon dioxide. When acid rain falls, they cause chemical reactions with rocks, and in the end altering the rocks structure. An example of chemical weathering is rust, when iron is oxidised, they form rust.
Even though rocks receive the same amount of exposure to weathering, some can erode faster depending on the structure and their environment. When the environment is hot and has a lot of water movement, the weathering process may take less time. Rocks such as limestone, and marble can weather at a faster rate because of its highly reactive chemical structure.
When rocks weather and erode too much, they might cause natural disaster such as landslides, mudflow, creeps, and slumping. Due to these sudden occurrences it can do severe damages to surrounding areas.
Mechanical Weathering is the alternation of rocks physically, and usually needs water to take place. Mechanical weathering can happen in many ways, which includes frost wedging, abrasion, and he growth of plant roots.
- Frost Wedging- when water freezes in little cracks of the earth's surface, the water expands, the expansion of ice breaks the rocks apart. This process takes a very long process, and happen very gradually.
- Abrasion- When rocks grind against another rock, and breaks of a part of the rock. In other words, a rock that breaks apart another rocks part. For example, when water carries a rock in its flow, and that rock breaks a part of another rock. This is called abrasion.
- Plant root- like any organisms, they grow. Trees grow in every part of their body. When roots grow into rocks, it has to make way for itself. In this process, the rocks are broken apart by roots that need to make space for their root to grow. This process may take years due to the slow growth of trees. When roots need room to grow, they break parts of the rock to male space, which is a form of weathering.
Another category in which weathering can occur is chemical weathering. This is the break down of rocks by chemical reactions. Chemical weathering usually takes place in regions where water is commonly found. Water being one of the most abundant liquid on the surface can be highly reactive to some substances. Usually clouds that form in the atmosphere can rain water that can be a bit acidic. This acid rain is called carbonic acid, the combination of water and carbon dioxide. When acid rain falls, they cause chemical reactions with rocks, and in the end altering the rocks structure. An example of chemical weathering is rust, when iron is oxidised, they form rust.
Even though rocks receive the same amount of exposure to weathering, some can erode faster depending on the structure and their environment. When the environment is hot and has a lot of water movement, the weathering process may take less time. Rocks such as limestone, and marble can weather at a faster rate because of its highly reactive chemical structure.
When rocks weather and erode too much, they might cause natural disaster such as landslides, mudflow, creeps, and slumping. Due to these sudden occurrences it can do severe damages to surrounding areas.
- Landslides- When a layer of the surface on a slope becomes loose due to heavy rain, and drops down the slope. A piece of the land disappears when something like this happens.
- Mudflows- The rapid flow of water and mud. When heavy rain takes place, the water saturates the surrounding soil, this causes the soil to turn into mud and joins the flow of water.
- Creeps- the gradual movement of soil down the slope due to the formation of ice. When ice forms in soil, it contracts then expands, letting loose much of the soil. The loose soil then slowly fall down the slope.
- Slumping- a like landslide, slumping is the sudden drop of weal units of soil down a slope.
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Erosion & shaping of earths surface by water
As explained above, water and sediments (rocks, and soil) erode and weather much of the surface. But where do the broken off pieces of the surface go. The answer is they settle down in many places such as waterbeds, ocean beds, and many other places. The deposition of these sediments is what creates the earth surface. Weathering and erosion breaks the earths surface and the flow of water deposit these broken and loose sediments onto new lands. Erosion begins when runoffs carry sediments in their flow, these flows create gullies something alike streams. These gullies combine and create a stream of water called a stress. These channel of water carry sediments in their flow and then deposits it in calm waters. When sediments flow or get caught in the flow, they are in the process of saltation. Saltation is when the flow of water carries sediments in the bottom of the streams bed.
Erosion of the surface can create magnificent formations throughout the globe. These formation form through the the process of constant erosion and weathering. These formations can include, V shaped valleys, waterfalls, meanders, oxbow lakes.
Erosion of the surface can create magnificent formations throughout the globe. These formation form through the the process of constant erosion and weathering. These formations can include, V shaped valleys, waterfalls, meanders, oxbow lakes.
- V shaped valley- the flow of the water near the source is very fast, therefore the sides of the mountains erode faster, when this happens, a v shaped valley forms. A V shaped valley can eventually become a waterfall.
- Floodplains- the flat land along a stream that is entirely covered with water in times of a flood. When a flood happens, the sediments that were carried down settles on the flood plain, leaving the plains with nutritious soil. Sometimes the flood may cause further erosion in the land.
- Waterfall- A sudden drop of the earths where water is falling.
- Meanders- Happens when the outside of a curved stream flows faster than the inside, creating a built up of sediment in the inside and erosion on the outside
- Oxbow Lake- when a new path is created the meanders connect, the no longer used meanders are deposited with sediment. The result is a separate curved lake.
When the flow of water become calm, the flow can no longer carry the sediments. The flow then deposits the sediments in new lands. When this happens they form new lands such as an alluvial fan, and a delta.
- Alluvial fan- when sediments settle in the bottom of a river, they create a fan shaped land where a lot of sediments rest.
- Delta- the meeting point of the river and a larger body of water. Sediments are also deposited in this region. Usually a triangular shape.
Other formation erosion can form is caves and underground lakes. Acidic rain has the capability to erode rocks more efficiently. Acidic rain can erode underground rock, and creates an open space underground. When the water table sinks the open space dries out and small droplets of from the surface drop into the cave. The droplets of water can then create mineral pillars called stalagmite. When the cave suddenly collapses it creates a sink in the surface called a sink hole.
Glaciers
As explained in the water cycle, condensed water vapour can precipitate various forms of water. Of which one of them is water. Water erosion and weathering had been explained above, but what would happen instead is the condensed water vapours precipitated snow? The answer is the gradual formation of glaciers. Glaciers are huge chunks of ice that can cover a vast area of land. Glaciers form when snow falls more than it melts, and when the snows layer over another, the bottom layer gets immense amounts of pressure due to gravity. The compression of snow forms ice, which then forms the glacier. But within glaciers are another two more categories which are Continental glaciers and Valley Glacier. Each of them have unique characteristics based on where they form.
Alike other forms of water, glaciers have the power and capability to shape the earths surface. This process of shaping the earth is called Glacial erosion. Glacial erosion is the process of breaking down rocks by the movement of glaciers. When glacial ice widens cracks that were originally there, the portion of the surface breaks off. When a part of the surface breaks off, it lies on the glacial bed and gradually gets frozen into the glacier. Due to the constant heating by the suns radiation, the glacier starts to melt, which means the glaciers move. The moment the glaciers move, the ice carries the rock with it while scraping the surface. In other words, the rock that had been frozen in the ice acts as the sand on a sand paper. This "sandpaper" starts eroding other parts of the glacial bed. When the erosion of the surrounding takes place, they create formations such as cirques, ridges, horns, and U-shaped valleys.
- Continental Glaciers- hick sheet of ice that covers a huge area of land, covers a continent or an island (e.g. Greenland, Antartica). This form of glacier has the most amounts of fresh water compared to other water bodies.
- Valley Glaciers- glaciers that form in high mountain valleys. These glaciers are said to have formed from a stream, possibly a stream where runoffs flowed.
Alike other forms of water, glaciers have the power and capability to shape the earths surface. This process of shaping the earth is called Glacial erosion. Glacial erosion is the process of breaking down rocks by the movement of glaciers. When glacial ice widens cracks that were originally there, the portion of the surface breaks off. When a part of the surface breaks off, it lies on the glacial bed and gradually gets frozen into the glacier. Due to the constant heating by the suns radiation, the glacier starts to melt, which means the glaciers move. The moment the glaciers move, the ice carries the rock with it while scraping the surface. In other words, the rock that had been frozen in the ice acts as the sand on a sand paper. This "sandpaper" starts eroding other parts of the glacial bed. When the erosion of the surrounding takes place, they create formations such as cirques, ridges, horns, and U-shaped valleys.
- Cirques- the formation of large bowl shaped valleys on mountainsides due to erosion by glaciers.
- Ridges- when several of these cirques meet, they create a sharp edge on mountains.
- Horns- a pointy top when summits come together and create a pyramid like peak.
- U -Shaped valleys- a U shaped valley that originated from a V-Shaped valleys. Continental glaciers have the characteristic of deepening the land and widening the valley. When glaciers erode these V-Shaped valleys, they cut deeper into it and therefore creates a U Shaped Valley.
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After the glacier completely melts, it leaves behind mark that would suggest that a glacier used to exist in this regions. This may be lumps in the surface, or barriers. The formations that form due to the movement of the glacier are, Lateral moraines, Medial moraines, end moraines, drumlins, eskers, and erratics. These formations are usually built by tills. Tills is glacial sediment that include gravel, sand and many others. The deposition of till is due to retreating glaciers. When glaciers are no longer developing, they start melting. This causes them to fall down the slope, and weather its path in the process.
- Lateral moraines- when till is deposited on the sides of the glacier
- Medial moraines- when two lateral moraines meet (2 glaciers) they create a medial moraine.
- End moraines- broad, rounded ridge of till that marks the furthest advancement of till
- Drumlins- long teardrop-shaped mounds of till that have been smoothened in the direction of the glaciers flow
- Eskers-ridges made from sand and gravel that were deposited in the bed of stream that flowed within the glacier
- Erratics- the large boulders of till glaciers carried, such as big rocks.
Wind erosion & OCEAN EROSION
We have covered mechanical and chemical weathering in previous sections, but there are 2 more forms of erosion. Of which are wind and ocean erosion. These forms of erosion usually only happen in specific places, and are not common throughout the globe. Wind erosion is erosion caused by wind, and usually takes place in dry ares such as deserts. Like any other form of erosion, there are various process of erosion, of which is abrasion and deflation if talking about wind erosion.
The sediments that are carried by the wind can deposit them and in result create new formations such as dunes and loess.
- Abrasion- We have previously covered this form of erosion, but as a summary, abrasion is the process of wind blowing sand against other rocks, slowly eroding them.
- Deflation- wind picks up and carries away loose surface rock, left with big rocks.
The sediments that are carried by the wind can deposit them and in result create new formations such as dunes and loess.
- Dunes- dunes are very similar to deserts. Sand that are blown by wind are deposited in these regions thus creating mountains of sand.
- Loess- is the a formation that forms when wind blow away dust instead of sand.
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The movement of wind can cause significant changes on earths surface, and beneath it. But any moving substances of particles can shape the earth, of which one of them is the erosion and weathering done by water. Water covers most of the earths surface and has played a significant role of shaping the earths surface. We have covered aspects of water such as runoff erosion due to precipitation, and glacial erosion, but we have not yet covered erosion and the shaping of earth caused by the ocean. The ocean are big masses of water that are seen throughout the globe that covers almost 71 % of the earths surface.
Oceanic water is not like runoffs or freshwater that we have covered but instead, it has a strong salty taste. This is called salinity, the proportion of dissolved salts in water. This salt is usually sodium chloride which is used in households. The salt in the water is the result of the dissolving of the surface rocks that contain salt, and there is almost 35 grams of salt in each kilogram of water. One of the most amusing and mysterious things about the ocean is its seabed. Because pressure increases and temperature decreases, thus we do not have the capability to. Pressure can become 50 times greater than what we experience on the surface. Adding to the pressure and temperature, light do not pass through 200 meters making it impossible to see beneath it without specific tools. Even though some parts of the ocean is inaccessible without specific tools and equipment, we can still explore and research the shallow part of the ocean. The depth of the ocean can range from 1km to a few meters. When the depth of the ocean is relatively shallow, we call it the continental shelf, this is a underwater landmass that extends from a continent to the oceanic bed. When the continental shelf comes to an end, it meets a steep descend called the continental slope which leads to the oceanic bed which can lie to almost 11km below surface.
One of the most unique characteristics about the ocean is its constant movement. The movement of water is called currents, caused by wind, rotation of the earth, and shape or size of the continent. Depending on the conditions and magnitude of these factors, they create different types of currents of which are surface and deep currents.
Another form of water movement in the ocean is upwelling.
Now, getting to the point, the movement of oceanic water can cause erosion in 2 ways. Of which are hydraulic action and abrasion. This process can create, rock coastline, arches, tall rocks, and caves.
Alike anything on this planet, it is constantly moving or changing shape. But putting this idea into ocean context, we have the phenomena of moving sand and the formation of beaches.
Oceanic water is not like runoffs or freshwater that we have covered but instead, it has a strong salty taste. This is called salinity, the proportion of dissolved salts in water. This salt is usually sodium chloride which is used in households. The salt in the water is the result of the dissolving of the surface rocks that contain salt, and there is almost 35 grams of salt in each kilogram of water. One of the most amusing and mysterious things about the ocean is its seabed. Because pressure increases and temperature decreases, thus we do not have the capability to. Pressure can become 50 times greater than what we experience on the surface. Adding to the pressure and temperature, light do not pass through 200 meters making it impossible to see beneath it without specific tools. Even though some parts of the ocean is inaccessible without specific tools and equipment, we can still explore and research the shallow part of the ocean. The depth of the ocean can range from 1km to a few meters. When the depth of the ocean is relatively shallow, we call it the continental shelf, this is a underwater landmass that extends from a continent to the oceanic bed. When the continental shelf comes to an end, it meets a steep descend called the continental slope which leads to the oceanic bed which can lie to almost 11km below surface.
One of the most unique characteristics about the ocean is its constant movement. The movement of water is called currents, caused by wind, rotation of the earth, and shape or size of the continent. Depending on the conditions and magnitude of these factors, they create different types of currents of which are surface and deep currents.
- Surface Currents- large stream o f ocean water that moves continuously in the same path, and are determined by wind. Wind that is caused by the unequal heating of earths surface.
- Deep current- caused by difference in density of ocean water. Deep ocean water is cold or high salinity which means it is denser, this causes the mixing of less dense water. This mixes the deep ocean waters and the surface waters.
Another form of water movement in the ocean is upwelling.
- Upwelling- movement of water from deep ocean to the surface. When the wind blows the warm water heated by the suns radiation away, the cold water from beneath rise up to take their place. In this process, the cold water carries up nutrients that feed some organisms.
Now, getting to the point, the movement of oceanic water can cause erosion in 2 ways. Of which are hydraulic action and abrasion. This process can create, rock coastline, arches, tall rocks, and caves.
- Hydraulic action- when water fills a crack with water, before one drains, another wave of water forces more water into the crack. In other words, the constant exertion of force causes the crack to gradually open
- Abrasion- the contact of sediments onto the coastal area
Alike anything on this planet, it is constantly moving or changing shape. But putting this idea into ocean context, we have the phenomena of moving sand and the formation of beaches.
- Deposition of Sediment- Sediments that are eroded from coastline or brought in by rivers is also deposited accumulate on coastline. These sediments then create beaches. If the sediments are deposited on a curve in the shoreline, the deposit is called a pit.
- Longshore Drift - is the zigzag movement of sand through the coastline. If a wave hits the shore at an angle, the waves carry sand up the beach at an angle. If this continues, sand will be constantly moving.