General Knowledge - Biology - Discussion
Discussion Forum : Biology - Section 1 (Q.No. 2)
2.
Ozone hole refers to
Discussion:
55 comments Page 1 of 6.
Bks said:
6 years ago
The different layers of the atmosphere
The atmosphere can be divided into layers based on its temperature, as shown in the figure below. These layers are the troposphere, the stratosphere, the mesosphere and the thermosphere. A further region, beginning about 500 km above the Earth's surface, is called the exosphere.
The red line on the figure below shows how temperature varies with height (the temperature scale is given along the bottom of the diagram). The scale on the right shows the pressure. For example, at a height of 50 km, the pressure is only about one thousandth of the pressure at the ground.
The Troposphere
This is the lowest part of the atmosphere - the part we live in. It contains most of our weather - clouds, rain, snow. In this part of the atmosphere the temperature gets colder as the distance above the earth increases, by about 6.5°C per kilometre. The actual change of temperature with height varies from day to day, depending on the weather.
The troposphere contains about 75% of all of the air in the atmosphere, and almost all of the water vapour (which forms clouds and rain). The decrease in temperature with height is a result of the decreasing pressure. If a parcel of air moves upwards it expands (because of the lower pressure). When air expands it cools. So air higher up is cooler than air lower down.
The lowest part of the troposphere is called the boundary layer. This is where the air motion is determined by the properties of the Earth's surface. Turbulence is generated as the wind blows over the Earth's surface, and by thermals rising from the land as it is heated by the sun. This turbulence redistributes heat and moisture within the boundary layer, as well as pollutants and other constituents of the atmosphere.
The top of the troposphere is called the tropopause. This is lowest at the poles, where it is about 7 - 10 km above the Earth's surface. It is highest (about 17 - 18 km) near the equator.
The Stratosphere
This extends upwards from the tropopause to about 50 km. It contains much of the ozone in the atmosphere. The increase in temperature with height occurs because of absorption of ultraviolet (UV) radiation from the sun by this ozone. Temperatures in the stratosphere are highest over the summer pole, and lowest over the winter pole.
By absorbing dangerous UV radiation, the ozone in the stratosphere protects us from skin cancer and other health damage. However chemicals (called CFCs or freons, and halons) which were once used in refrigerators, spray cans and fire extinguishers have reduced the amount of ozone in the stratosphere, particularly at polar latitudes, leading to the so-called "Antarctic ozone hole".
Now humans have stopped making most of the harmful CFCs we expect the ozone hole will eventually recover over the 21st century, but this is a slow process.
The Mesosphere
The region above the stratosphere is called the mesosphere. Here the temperature again decreases with height, reaching a minimum of about -90°C at the "mesopause".
The Thermosphere and Ionosphere
The thermosphere lies above the mesopause, and is a region in which temperatures again increase with height. This temperature increase is caused by the absorption of energetic ultraviolet and X-Ray radiation from the sun.
The region of the atmosphere above about 80 km is also caused the "ionosphere", since the energetic solar radiation knocks electrons off molecules and atoms, turning them into "ions" with a positive charge. The temperature of the thermosphere varies between night and day and between the seasons, as do the numbers of ions and electrons which are present. The ionosphere reflects and absorbs radio waves, allowing us to receive shortwave radio broadcasts in New Zealand from other parts of the world.
The Exosphere
The region above about 500 km is called the exosphere. It contains mainly oxygen and hydrogen atoms, but there are so few of them that they rarely collide - they follow "ballistic" trajectories under the influence of gravity, and some of them escape right out into space.
The Magnetosphere
The earth behaves like a huge magnet. It traps electrons (negative charge) and protons (positive), concentrating them in two bands about 3,000 and 16,000 km above the globe - the Van Allen "radiation" belts. This outer region surrounding the earth, where charged particles spiral along the magnetic field lines, is called the magnetosphere.
The atmosphere can be divided into layers based on its temperature, as shown in the figure below. These layers are the troposphere, the stratosphere, the mesosphere and the thermosphere. A further region, beginning about 500 km above the Earth's surface, is called the exosphere.
The red line on the figure below shows how temperature varies with height (the temperature scale is given along the bottom of the diagram). The scale on the right shows the pressure. For example, at a height of 50 km, the pressure is only about one thousandth of the pressure at the ground.
The Troposphere
This is the lowest part of the atmosphere - the part we live in. It contains most of our weather - clouds, rain, snow. In this part of the atmosphere the temperature gets colder as the distance above the earth increases, by about 6.5°C per kilometre. The actual change of temperature with height varies from day to day, depending on the weather.
The troposphere contains about 75% of all of the air in the atmosphere, and almost all of the water vapour (which forms clouds and rain). The decrease in temperature with height is a result of the decreasing pressure. If a parcel of air moves upwards it expands (because of the lower pressure). When air expands it cools. So air higher up is cooler than air lower down.
The lowest part of the troposphere is called the boundary layer. This is where the air motion is determined by the properties of the Earth's surface. Turbulence is generated as the wind blows over the Earth's surface, and by thermals rising from the land as it is heated by the sun. This turbulence redistributes heat and moisture within the boundary layer, as well as pollutants and other constituents of the atmosphere.
The top of the troposphere is called the tropopause. This is lowest at the poles, where it is about 7 - 10 km above the Earth's surface. It is highest (about 17 - 18 km) near the equator.
The Stratosphere
This extends upwards from the tropopause to about 50 km. It contains much of the ozone in the atmosphere. The increase in temperature with height occurs because of absorption of ultraviolet (UV) radiation from the sun by this ozone. Temperatures in the stratosphere are highest over the summer pole, and lowest over the winter pole.
By absorbing dangerous UV radiation, the ozone in the stratosphere protects us from skin cancer and other health damage. However chemicals (called CFCs or freons, and halons) which were once used in refrigerators, spray cans and fire extinguishers have reduced the amount of ozone in the stratosphere, particularly at polar latitudes, leading to the so-called "Antarctic ozone hole".
Now humans have stopped making most of the harmful CFCs we expect the ozone hole will eventually recover over the 21st century, but this is a slow process.
The Mesosphere
The region above the stratosphere is called the mesosphere. Here the temperature again decreases with height, reaching a minimum of about -90°C at the "mesopause".
The Thermosphere and Ionosphere
The thermosphere lies above the mesopause, and is a region in which temperatures again increase with height. This temperature increase is caused by the absorption of energetic ultraviolet and X-Ray radiation from the sun.
The region of the atmosphere above about 80 km is also caused the "ionosphere", since the energetic solar radiation knocks electrons off molecules and atoms, turning them into "ions" with a positive charge. The temperature of the thermosphere varies between night and day and between the seasons, as do the numbers of ions and electrons which are present. The ionosphere reflects and absorbs radio waves, allowing us to receive shortwave radio broadcasts in New Zealand from other parts of the world.
The Exosphere
The region above about 500 km is called the exosphere. It contains mainly oxygen and hydrogen atoms, but there are so few of them that they rarely collide - they follow "ballistic" trajectories under the influence of gravity, and some of them escape right out into space.
The Magnetosphere
The earth behaves like a huge magnet. It traps electrons (negative charge) and protons (positive), concentrating them in two bands about 3,000 and 16,000 km above the globe - the Van Allen "radiation" belts. This outer region surrounding the earth, where charged particles spiral along the magnetic field lines, is called the magnetosphere.
(3)
Pradeep said:
9 years ago
Ozone hole refers to decrease in thickness of Ozone layer in Stratosphere.
As pollution (Co2, Co, So2, So3 gases present in the air) increases and all the chlorofloro carbons comes from earth then ozone layer thickness decreases, as a result. Ultra Violate rays of the sun directly come on earth and causes us to cance.
As pollution (Co2, Co, So2, So3 gases present in the air) increases and all the chlorofloro carbons comes from earth then ozone layer thickness decreases, as a result. Ultra Violate rays of the sun directly come on earth and causes us to cance.
Amitkumar said:
10 years ago
I think the responsible facts of global warming are chlorofluorocarbon, methane and carbon di oxide. Due to heavy pollution the environment of our Earth is is being polluted. Day by day the ozone layer is decreasing. So we can facing the ultraviolet rays of sun that is very harmful for us and it causes cancer.
Dhruvil said:
1 decade ago
Ozone hole refers to a hole in ozone layer which is present in stratosphere and responsible for the absorption of ultraviolet radiations.
Hole in ozone layer is produced due to large amount of pollutants in air such as Co2, Co, So2, So3 gases present in the air.
Hole in ozone layer is produced due to large amount of pollutants in air such as Co2, Co, So2, So3 gases present in the air.
Anuja Singh said:
1 decade ago
As global warming is increasing and people are cutting trees for their greed due to that global warming is increasing and amount of pollution is increasing in the enviorment thats the reason why we all are facing these problems occuring in our enviorment.
Msrinivasrao said:
8 years ago
If we take an example of a filter, if we don't take care of it and make it dirty. And if we don't clean it, it tends to be dirty and filter spoils. Same like this ozone layer also will spoil like a filter because of pollution made by humans.
Faisal Mirza said:
9 years ago
There are many reasons to increasing temperature. But main reasons is increasing pollution in our environment and also increased temperature by direct UV rayes comes on earth from the Sun.
Anil, said:
1 decade ago
As pollution increase all the chlorofloro carbons comes from our earth then ozone layer thickness is decrease as a result UV rays of sun directly comes on earth and causes us to cancer .
Mithun said:
1 decade ago
Ozone layer filters the UV rays from the sun which causes skin cancer. Because of pollution the ozone layer is depleting. If it completely depletes OZONE we would be in DANGER ZONE.
Promise said:
5 years ago
The decrease in thickness of the ozone layer due to global warming, CFC and pollution eases the passes of ultraviolet rays into the earth which is very Poisonous to human health.
Post your comments here:
Quick links
Quantitative Aptitude
Verbal (English)
Reasoning
Programming
Interview
Placement Papers