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Answer:

Humans affect erosion rates in a number of ways across the globe.

Explanation:

Humans affect erosion rates in a number of ways across the globe. Studies have shown that humans now cause more erosion than natural processes do.

http://www.dartmoor.gov.uk/learningabout/lab-printableresources/lab-factsheetshome/lab-erosion

Deforestation can drastically increase erosion rates, as healthy forests and ecosystems are filled with plants and the roots of these plants hold soil in place. Without it, we see increased erosion due to wind (soil and sand blown from place to place) and water (increased runoff).

Agricultural practices can have a very significant impact on erosion rates. Certain practices cause more erosion than others. When livestock are permitted to graze the grass to very low levels, this increases the likelihood of erosion, as soil can be transported more easily due to wind and water.

Growing monocultures (one type of crop) rather than a diversity of crops also contributes to erosion as do other forms of intensive agriculture where nutrients are depleted form the soil and the soil cannot recover in between growing seasons.

https://www.tn.gov/agriculture/article/ag-farms-arcf

The use of certain chemicals in agriculture can also contribute to increased soil erosion, as these chemicals disrupt the organisms that live in the soil and change the chemical composition of the soil.

Human activities such as repeatedly walking or biking the same trails or areas can also contribute to erosion slowly over time. Forest fires also contribute to soil erosion, as vegetation previously holding the soil in place is often destroyed. Mining increases erosion, as soil is exposed during this process and thus available to be moved by wind and water in addition to the amount of soil and rock moved intentionally by humans. Urbanization also contributes to erosion, as vegetation is lost and replaced with buildings.

http://www.permamatrix.com/or-by-man/

Erosion rates can be slowed by reforesting areas, using chemicals wisely on agricultural areas, growing diverse crops and using less intensive agricultural procedures, limiting resource extraction, and so forth.

To read more about this problem, see this page by WWF.

Answer:

The global wind belts are the three wind belts or patterns of movement that cover the planet.

Explanation:

The global wind belts are the three wind belts or wind patterns that cover the planet: the tropical easterlies (or the trade winds) are found near the equator, the polar easterlies are found at the north and south poles, and the prevailing westerlies are found between the two.

The above wind belts exist in both hemispheres (see image below).

http://ww2010.atmos.uiuc.edu/(Gh)/wwhlpr/hurricane_globalwinds.rxml

Global winds blow from high to low pressure at the base of the atmospheric circulation cells. The polar easterlies are at the base of the polar atmospheric cell, the prevailing westerlies are at the base of the Ferrel Cell, and the tropical easterlies are at the base of the Hadley Cell.

http://www.climateprediction.net/climate-science/glossary/global-atmospheric-circulation/

To learn more, watch this video:

Answer:

The overall reaction that occurs within a hydrogen fuel cell is the same as that for combustion of hydrogen. This reaction is highly exothermic. Instead of producing heat, electric potential energy is generated.

Explanation:

A fuel cell is a type of electrochemical cell in which the reacting chemicals are continually added (one being oxygen), and products are removed (unlike a car battery or dry cell which is a closed system).

In the case of a hydrogen fuel cell, the process relies on a reaction that involves an equation identical to burning hydrogen

#2H_2 (g) + O_2 (g) rarr 2 H_2O (g#

This is an exothermic reaction (produces energy), in a fixed amount regardless of the process used to carry it out. The main difference is that the reaction is carried out in an electrochemical cell, with two half-reactions that take place at different locations within the cell.

http://www.hydrogenics.com/technology-resources/hydrogen-technology/fuel-cells/

At the cathode of the cell, hydrogen gas is supplied, and the process that occurs is the oxidation of the hydrogen into #H^+# ions:

#2H_2 (g) rarr 4 H^+ 4 e^-#

The hydrogen ions drift through the permeable anode material, the electrolyte (typically a solution of KOH) and arrive at the cathode. Here, they react with oxygen from the air in a reduction:

#O_2 (g) + 4H^+ + 4e^-##rarr 2 H_2O (g)#

This cell generates electrical energy with a cell potential of about 1.25 volts.

The combined "sum" of these two half-reactions (as they are known) yields an equation that is the same as the one that describes combustion of hydrogen gas.

Since the overall reaction is the same, the total energy produced is the same, but the efficiency of the cell (the portion of the energy that can be used to do useful work) is far greater than combustion provides.

You may want to check out this site:

http://www.hydrogenics.com/technology-resources/hydrogen-technology/fuel-cells/

Answer:

They are structure used to change the Potential Energy of Water into Electric Energy.

Explanation:

AEP.com
[AEP’s Smith Mountain Hydro Project on the Roanoke River southeast of Roanoke, Virginia]

Have a look at the diagram:
enter image source here

In (A) you have a water reservoir (a lake of other water basin) where water is stored ready to be used. The water is secured by the actual dam (B) that is a kind of big wall that keeps the water from flowing down. The water in the reservoir has Potential Energy because it is at a higher level compared to, say, the valley below.

We use a pipe (C) to let the water flow down towards a structure (D) where is housed a big turbine connected to a dynamo.
The turbine (a kind of propeller) is moved by the water and acting on the dynamo produces electrical energy that, after transformation to high voltage, will be transmitted through a line (E).

The dynamo is normally called a Generator:
USGS Water Resources

Answer:

See below.

Explanation:

Ozone depletion is primarily caused by human activities. The main effect of ozone depletion is an increase in UV-B rays reaching the earth's surface.

Causes : chlorofluorocarbon (CFCs), halons, and other compounds deplete the ozone layer. These chemicals are found in cleaning agents, aerosols, insulating foam, and refrigerants. CFCs and halons break down into chlorine and bromine which in turn destroy the ozone layer.

http://eschooltoday.com/ozone-depletion/what-is-ozone-depletion.html

Effects :
Humans: an increase in UV-B rays means a higher risk of skin cancer, eye cataracts, and blindness. Read more here.

Marine life: Phytoplankton and zooplankton are very sensitive to the amount of light in their environment, and increases in UV-B rays would greatly affect them. Because these organisms are the base of the food chain, declines in their numbers would likely have wide-reaching effects for all marine life. Read more here.

Plants: UV-B rays negatively affect plants, including crops humans rely on. An increase in UV-B rays can mean smaller leaf size, decreased plant growth, and lower quality crops for humans. Plants form the basis for most food chains, thus negative effects would likely cascade to those organisms relying on them. Plants are also very important in terms of respiration, photosynthesis, soil stability, and a decline in plant productivity/reduced plant growth would potentially affect soil erosion and productivity and the carbon cycle. Read more here.

Answer:

Humans impact the water cycle in numerous ways.

Explanation:

Humans affect the water cycle in numerous ways. Some of our actions purposefully affect the water cycle and other human activities have unintentional consequences on the water cycle.

Purposefully changing water cycle :

http://www.caryinstitute.org/educators/teaching-materials/water-watersheds
The image above shows some examples of how we manipulate various sources of water on earth. We pull water out of the ground in order to use it. We change the flow of water using irrigation. We dam lakes and rivers for electricity and to create manmade lakes and ponds. The Colorado River in the US no longer reaches the ocean at times because humans have altered it so much.

Irrigation:
http://loticbiome.blogspot.com/2016_02_01_archive.html

Groundwater usage in India:
http://www.wri.org/blog/2015/02/3-maps-explain-india’s-growing-water-risks

Indirect effects :
Climate change is causing numerous changes to the water cycle. Sea levels are rising in some areas and dropping in others, glaciers are retreating and disappearing affecting rivers, droughts are happening more frequently in some regions and floods in other areas, coastlines are changing and some islands are disappearing, the polar ice cap is melting, and so forth.

The use of pesticides, herbicides, and excess nitrogen for farming runs off into rivers and streams and pollutes groundwater. Deforestation, whether for timber or to clear land for agriculture or development, increases runoff. Certain emissions from industry cause acid rain .

Pollution of groundwater:
https://water.usgs.gov/edu/earthgwquality.html

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