The greenhouse effect - class-IX

Our atmosphere allows the high frequency radiation (Infrared rays) to pass through it, which comes from sun. This radiation reaches to earth and after some absorption (this radiation is also absorbed and radiated by green house gases), earth reflects back low frequency radiation (Infrared rays) which cannot pass through the atmosphere. This radiation is trapped in our atmosphere and keeps our atmosphere warm, this is called green house effect.

Process of warming of planet's surface and its lower atmosphere by the absorption of infrared radiations of long wavelength given out from the surface of a planet is known as green house effect.  In 1824, Joseph Fourier discovered the green house effect.

Carbon dioxide, methane, and ozone are well-known greenhouse gases. Sulphur dioxide is primarily an air pollutant that causes acid rain, not a primary greenhouse gas.

The ozone layer absorbs harmful ultraviolet radiation, specifically UV-C and some UV-B, which have wavelengths shorter than approximately 300 nm (3 * 10^-7 m).

In the given options,other than nitrogen gas,rest all the gases has the capability of trapping the heat rays reflecting from the earth.(they trap the heat rays because they have certain properties which are either enhanced or reduced due to heat)

1. Carbon dioxide 
   2. Methane 
   3. Nitrous oxide 

A greenhouse gas is a gas that absorbs and emits radiant energy within the thermal infrared range. Greenhouse gases cause the greenhouse effect on planets. The primary greenhouse gases in Earth's atmosphere are water vapour $(H _2O)$, carbon dioxide $(CO _2)$, methane $CH _4)$, nitrous oxide $(N _2O)$ and ozone $(O _3)$. Among the given gases, $CO _2$ is not present in very high quantity.

Scientists use these factors to calculate a gass global warming potential, which measures how much heat it absorbs per pound.

Process of warming of planet's surface and its lower atmosphere by the absorption of infrared radiations of long wavelength given out from the surface of a planet is known as green house effect.  In 1824, Joseph Fourier discovered the green house effect. The earth's transparent for the infrared radiations of short wavelengths coming from the sun. The high energy radiations such as X rays, gamma rays, UV rays are absorbed by the ozone layer while the low energy radiations namely infrared radiations of long wavelength and radio waves are reflected back into the space.

Since greenhouse gases trap heat rays (infrared rays) which due to irradiation keeps the earth warm.

Process of warming of planet's surface and its  lower atmosphere by the absorption of infrared radiations of long wavelength given out from the surface of a planet is known as green house effect. In 1824, Joseph Fourier discovered the green house effect.

They trap the heat rays because they have certain properties which are either enhanced or reduced due to heat.Capturing infrared rays is a characteristic properties of greenhouse gases.

The greenhouse effect itself occurs when short-wave solar radiation (which is not impeded by the greenhouse gases) heats the surface of the Earth, and the energy is radiated back through the Earth's atmosphere as heat, with a longer wavelength. In the wavelengths 5-30m a lot of this thermal radiation is absorbed by water vapour and carbon dioxide, which in turn radiate it, thus heating the atmosphere and land and ocean surface. This is natural and what keeps the Earth habitable.

Without the greenhouse effect overnight temperatures would plunge and the average surface temperature would be about minus 18C, about the same as on the moon, which lacks the shroud of our atmosphere.
Thus Option A is correct.

Methaneemitted from landfills, coal mines, oil/gas operations, and agricultural livestockaccounted for 10 percent of U.S. greenhouse gas emissions.

Trichlorofluoromethane is a type of fluorocarbon. Fluorocarbons were not present in the atmosphere before 1750. Today trichlorofluoromethane is present in the atmosphere at 242 to 244 parts per trillion (ppt).

Electricity production accounted for 31 percent of U.S. greenhouse gas emissions in 2013, followed by transportation at 27 percent.

Vegetation and the oceans absorb somebut not all $CO _2$ emissions. Power plants can use carbon capture and sequestration technology to reduce emissions.

All the gases which has the properties that may be influenced by heat rays,has the capability to absorb infrared rays and hence act as greenhouse gases.

The green house gas is $CO _2$.
A greenhouse gas (sometimes abbreviated GHG) is a gas in an atmosphere that absorbs and emits radiation within the thermal infrared range. This process is the fundamental cause of the green house effect. The primary greenhouse gases in the Earth's atmophere are water vapor, $CO _2 $, $CH _4$ , nitrou oxide and Ozone.
Thus Option D is correct.

HFCs are coolants used in air conditioners and refrigerators that have a high global warming potential of about $10,000$.

This fluorinated gas absorbs the most heat over a hundred-year period. Its global warming potential is 23,500, compared to 28 for methane and 1 for carbon dioxide.

On average, methane lingers in the atmosphere for $12$ years, while $CO _2$ can remain for thousands of years.

Methane allows sunlight (shortwave radiation) to pass through the atmosphere freely, where it is then partially absorbed by the surface of the Earth. But some of this energy bounces back out towards space as heat. Of the heat emitted back to space, some is intercepted and absorbed by methane in the atmosphere. This molecular structure allows it to absorb some of the escaping heat and then re-emit it towards the Earth which increases global temperatures.

The greenhouse effect simply describes the fundamental role our atmosphere plays in sustaining life on Earth. Energy from the sun in the form of sunlight passes through our atmosphere and warms the surface of the Earth which then emits the energy back into the atmosphere in the form of infrared radiation. Greenhouse gases, which make up only about one per cent of the atmosphere, absorb and re-emit some of this heat, preventing much of it leaving the Earth's atmosphere. This keeps the blue planet at a comfy temperature to sustain life.
But over time, climate scientists argue, our atmosphere has accumulated more greenhouse gases, in particular carbon dioxide, methane, nitrous oxide and fluorocarbons. This increased concentration of atmospheric gases traps more heat close to the Earth's surface in the lower atmosphere and increases the average global temperature. This process, called the 'enhanced greenhouse effect', is fundamental to global warming.

These emissionsmostly from burning coal, oil, and natural gasaccounted for 82 percent of all U.S. greenhouse gases in 2013.