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Environmental Science CT

The Sixteenth

Environmental Science An Essential Note of Environmental Science

Chapter: Atmosphere

Prepared By- Jannatul Ferdous Sonya

Sumaiya Khatun Rasidul Islam Rana

Md. Rashedur Rahman Tanvir University of Rajshahi

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Questions:

What is condensation and condensation nuclei?

Narrate the different types of precipitation. 6(13)

Write a brief account of the monsoon of Bangladesh mentioning its importance in agriculture. 10(13)

Briefly describe the different forms of condensation.

Describe the vertical layers of atmosphere. 4(13)

Write down the composition of atmospheric layer and importance of

atmosphere on agriculture 4(14)

What is Environmental laps rate?

Short notes:

Solar radiation 2.5(13,15)

What is condensation and condensation nuclei?

Condensation:

Condensation is the change of state of water from vapour to liquid

Condensation nuclei:

The particle on which condensation of water vapour takes place is known as

condensation nuclei. The substances are microscopic or submicroscopic like salt

particles, dust particles etc. These are hygroscopic in nature that means they

have affinity towards water

Narrate the different types of precipitation. 6(13)

Precipitation:

Precipitation can be defined as falling of water drops or ice particles that have

formed by condensation in atmosphere.

Different forms of precipitation

A. Liquid form: drizzle, rain, shower

B. Solid form: snow & hail.

C. Mixed form: sleet

Composition and vertical layers of atmosphere, Importance of atmosphere Solar radiation: Nature and distribution of solar radiation on earth's surface. Types of condensation, Types of

precipitation, Cloud formation and types, Temperature: Diurnal and annual range of temperature. Monsoon of Bangladesh, Importance of

monsoon in agriculture

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1. Drizzle:

It is more or less uniform precipitation of very small

& numerous raindrops, which are carried away even by light winds. The average

drizzle drop is 0.5 mm in size.

2. Rain:

Rain is defined as precipitation of drops of liquid water. The cloud consists of

minute droplets of water of diameter 0.02 mm. When the size of water droplets

increases they fall down as rain. The droplets are formed by rapid condensation.

The raindrops have a size as much as 5 mm.

3. Shower:

Precipitation lasting for short time with relatively clear intervals is called as

shower. This occurs from the passing clouds. This is also known as intermittent

rain.

4. Snow:

Snow is defined as precipitation of water in the solid form if small or large ice

crystals. It occurs only when the condensing medium has a temperature below

freezing temperature i.e. 0°C. Snow can be beneficial or injurious to plant in a

number of ways.

5. Hail:

Precipitation of small pieces of ice with diameter ranging from 5 to 50 mm or

something more is known as hail. It is the most destructive form of precipitation

produced during thunder / storms

6. Sleet:

It refers to precipitation in the form of a mixture of rain & snow . It consists of

small pellets of transparent ice, 5 mms or less in diameter.

Write a brief account of the monsoon of Bangladesh mentioning its

importance in agriculture. 10(13)

Monsoon

The word monsoon has originated from the Arabic term “Mawsim” which means

season. The monsoon winds change direction with season. There are two distinct

monsoon winds namely South West monsoon winds& North-East monsoon

winds. Wind blows from the South-West for 6 months during the summer & from

the North-East for another 6 months during the winter across the country. The

South-West monsoon is noticed during the summer& North-East monsoon is

noticed during the winter over Bangladesh.

Importance of monsoon in agriculture

i. Ours is an agricultural country. We need water for agriculture. Water

originated due to monsoon rainfall is used in agriculture

ii. Where irrigation facility is not convenient, monsoon rainfall is the principal

source of water there

iii. Winter season is dry & rain crops grow well during this time. Rainfall

occurred due to monsoon wind is essential for rain crops

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iv. From geographic point of view, Bangladesh is located in the tropics. Yet

Bangladesh's climate is temperate or moderate due to monsoon rainfall

v. Bangladesh's main crops such as rice, jute, sugarcane, tobacco, tea etc. are

dependent on monsoon rainfall.

vi. Heavy rainfall occurs during summer & rainy season due to monsoon winds.

Hence rivers get afloated. Silt deposition increases fertility.

Briefly describe the different forms of condensation.

Forms of condensation

Condensation: Condensation is the change of state of water from vapour

to liquid

Condensation nuclei: The particle on which condensation of water

vapour takes place is known as condensation nuclei. The substances are

microscopic or submicroscopic like salt particles, dust particles etc. These

are hygroscopic in nature that means they have affinity towards water

A. Condensation near the ground: dew, fog, mist, frost

B. Condensation in the troposphere: cloud, precipitation

1. Dew:

Dew consists of tiny droplets of water produced by condensation on surface

objects such as plant leaves, window glasses etc. Clear sky, calm air an

appreciable quantity of moisture in the air is the necessary conditions for dew

formation. Dew is important for agriculture. It is a Primary source of water in

certain arid regions. It helps the crops which are cultivated without water

2. Frost:

Frost occurs when the dew point temperature of air falls below the freezing point.

When condensation starts with temperature below 0°C, the water vapor in air

passes directly from the gaseous to solid state. Frost is always injurious to

vegetation. It affects crop life, castor, tobacco, tomato, cotton, cumin etc.

3. Fog:

Fog is defined as almost microscopically small drops of water condensed form &

suspended in air near the surface of the earth. Fogs are minute water droplets

suspending in the atmosphere near the ground. When fog occurs, the wind is

calm & relative humidity is more than 75%. Fogs restrict horizontal visibility

according to its density.

4. Mist:

Mist is densed fog. It disappears with rising sun. These are the wet hygroscopic

particles suspended in the air.

5. Smog:

When smoke & fog are mixed which results into poor visibility is known as smog.

It is more common in city & industrial areas. It is the pollution in the air.

N.B. forms = condensation + condensation nuclei + forms.

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Describe the vertical layers of atmosphere. 4(13)

Write down the composition of atmospheric layer and importance of

atmosphere on agriculture 4(14)

Atmosphere:

The multi-layered gaseous envelope surrounding the planet earth is called

atmosphere.

The atmosphere remains in contact with all the major types of environment of

earth, interacting with them and greatly affecting their ability to support life. It

filters sunlight reaching the earth, affect climate, and is a reservoir of several

elements essential for life.

Various Zones of Atmosphere

The atmosphere is divided into five distinct layers or zones

1. Troposphere

2. Stratosphere

3. Mesosphere

4. Ionosphere

5. Exosphere

The troposphere separates the stratosphere from the troposphere and

stratosphere separates mesosphere from stratosphere.

1. Troposphere:

It is the lowest region of atmosphere which subjects to differential heating,

temperature inversions and convection currents and which extends from the

surface of the earth up to a height of 8 to 10 km at polar latitudes(poles), 10to

12 km at moderate latitudes and 16 to 20 km at the equator. For the organisms,

troposphere forms a most important zone of atmosphere. Many important

climatic events such as cloud formation, lightening, thundering, thunder storm

formation etc. all take place in troposphere. In this zone the percentage

concentration of different gases in air does not vary with an increase in height.

But the water vapour content in air depends upon the weather (e.g. part of the

troposphere over an ocean carries more moisture than that over a land surface)

and it decreases sharply with an increase in height as does the air temperature.

Air temperature in this zone gradually decreases with height at the rate of about

6.50C per km (more specifically 50C per km in the lower troposphere and 70C per

km in the upper troposphere). In fact, towards the upper layers of troposphere,

the temperature may decrease up to -60°C. Upper region of the troposphere

has a narrow boundary called the tropopause which has a constant temperature.

Further, the non-uniform heating of the ground surface by sun's radiations

produces ascending and descending air current which causes turbulence and

mixing of air masses vertically. Moreover average air pressure at the earth

surface is 1014 millibar (1 millibar =1/1000 bar, 1 bar = 1.019kg per cm2 close

to 1 atmosphere, 1.332 millibars = 1 millimeter of Hg act an altitude of 5 km, the

air pressure is half that at the surface, at l1 km it is 225 millibars and at 17 km

it is only 90 millibars)

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2. Stratosphere:

Next to troposphere is the second zone, called stratosphere, which is about 30

km in height. This zone is free from clouds and aeroplanes usually fly in its

lower zone. The temperature of stratosphere increases up to 900C and such an

increase in temperature is due to ozone formation under the influence of

ultraviolet component of sunlight. Such a layer of ozone is called ozonosphere.

In ozonosphere, the sunlight ionize oxygen to ozone by photochemical

dissociation. The ozonosphere completely absorbs solar radiation, ultraviolet

radiation from the sun and also a lot of the solar infra-red, thus becoming

warmer than adjacent layers above or below. There is a serious threat to this

ozone layer now due to the harmful effects of gaseous pollutants. A big hole (i.e.

thinning of the O3 layer) has occurred in it, above the antarctic region. Upper

layers of stratosphere form stratopause.

3. Mesosphere:

Stratosphere is followed by next zone called mesosphere which is 40 km in

height. In mesosphere, temperature shows again a decrease up to -80°C, Upper

layers of this zone form the Mesopause.

4. Ionosphere

The remaining part of atmosphere above the mesosphere, up to the height of

about 300 km above earth's surface, is called ionosphere, Ionosphere contains

several layers of ionized air Thus, most of the gaseous components which

become ionized under the influence of radiant energy remain as ions. Ionosphere

reflects short radio waves, making telecommunication possible over long

distances

5. Exosphere:

The exosphere is the outer fringe of earth's atmosphere and outer space begins

after it. The air density is very low in his zone; hydrogen being dominant

clement of it.

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Importance of Atmosphere on agriculture:

The importance of the atmosphere on agriculture is as follows-

i. It supplies the necessary precipitation or moisture.

ii. It protects plant from harmful extraterrestrial radiations like UV, by

absorbing it though ozone.

iii. It provides the necessary CO2 which is basic input required to run

photosynthesis process in plants to build biomass.

iv. It provides the necessary medium for the transport of pollens, seeds spores

and insects.

v. Atmosphere is a big reservoir of nitrogen. Some plants and microbes can

fix this nitrogen for plant growth e.g. Azolla, pinara, Azotobacter.

vi. It maintains the warmth of the plannet through its greenhouse effect,

avoiding the temperature to fall to too extreme limits.(The earth‟s

temperature in the absence of atmosphere would have been +950C

(day),and -1450C (Night). In that situation, we can‟t even think about crop

cultivation.

vii. Many physical chemical and hydrological processes responsible for weather

and climate occur in atmosphere only. We know weather and climate affect

agriculture greatly. Thus atmosphere plays role on Agriculture.

What is Environmental laps rate?

Environmental laps rate:

For every one kilometer increase of height from ground, temperature decreases

6.50C. It is called environmental laps rate.

Short notes:

Solar radiation 2.5(13,15)

Solar radiation:

Solar radiation is radiant energy emitted by the sun, particularly

electromagnetic energy.

Solar radiation is the radiation, or energy we get from the sun. It is also

known as short-wave radiation.

About half of the radiation is in the visible short-wave part of the electromagnetic

spectrum. The other half is mostly in the near-infrared part, with some in the

ultraviolet part of the spectrum.

The portion of this ultraviolet radiation that is not absorbed by the atmosphere

produces a suntan or sunburn on people who have been in sunlight for extended

periods of time. Of the 3.8 × 1033 ergs emitted by the Sun every second, about 1

part in 120 million is received by its attendant planets and their satellites. The

small part of this energy intercepted by Earth (the solar constant, on average 1.4

kilowatts per square meter) is of enormous importance to life and to the

maintenance of natural processes on Earth‟s surface (sees also sunlight). The

energy output of the Sun has its peak at a wavelength of 0.47 micrometer

(0.000019 inch; a micrometer is 10−6 meter), and the Sun radiates about 8

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kilowatts per square cm of its surface. Measurements for solar radiation are

higher on clear, sunny day and usually low on cloudy days. When the sun is

down, or there are heavy clouds blocking the sun, solar radiation is measured at

zero.

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Questions:

What is greenhouse effect? Write down the greenhouse effect on agriculture. 4(13)

What is greenhouse effect? Describe the greenhouse effect on

agriculture. 6(15)

What do you mean by Ozone layer depletion?

Discuss the causes of ozone layer depletion. 4(13)

Describe the causes of ozone layer depletion. 4(15)

Briefly describe the effects of ozone layer depletion on organism.

How CFCs destroy ozone layer?

Write down the Mechanism of ozone layer depletion by CFCs

Write down the function of ozone layer.

What do you mean by weather & climate? 2(14)

Describe the impact of climate change on agriculture.

Describe the factors affecting the climate. 8(14)

Difference between climatology & meteorology 1.5(14)

Write down the consequences of global warming on the people living

the coastal areas. 6(15)

Write down the present status of CO2 in atmosphere

What are CFCs? Write down the uses of CFCs

Short notes:

Global warming 2.5(14

Global warming and climate change

What is greenhouse effect? Write down the greenhouse effect on agriculture. 4(13)

What is greenhouse effect? Describe the greenhouse effect on agriculture. 6(15)

Introduction, greenhouse gases, causes of ozone layer depletion, control of global warming. Global climate change and its consequences.

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Greenhouse effect / Global warming:

Global warming is defined as the increase in the temperature of globe due to transmission of incoming short waved radiation from the sun & the absorbance

of outgoing long waved radiation from the earth. This has been aggravated by the building up of some gases namely CO2, CH4,

N2O & CFCs. These are collectively called as greenhouse gases & they inhibit the outgoing radiation from the earth & upset earth‟s heat balance. The phenomenon is called greenhouse effect.

In the ordinary usage it simply means that the average air temperature will increase as a result of the built up of greenhouse gases in the atmosphere.

Effect of green house on Agriculture:

Scientists and policy makers alike have recognized that agricultural yields are at risk from climate change and human-caused emissions. Carbon dioxide is the

largest driver of climate change, but in a new study, Shindell found that other anthropogenic, or human-sourced, emissions cause more damage to crop yields.

Methane (mainly from natural gas production and livestock), halocarbons (used in refrigeration and air conditioning), and black carbon (from fossil and biomass fuels) all contribute to climate change to varying degrees.

The research says that the greatest damage to crops per ton comes from black

carbon and from gases used in refrigeration. Methane emissions are also very harmful to plants because the gas increases surface ozone that causes harmful chlorosis, or a yellowing of the leaves.

The effects of carbon dioxide are more complicated. Carbon dioxide fertilizes

plants, which means as the amount of the gas in the atmosphere increases, crop yields initially increase as well. But as carbon emissions continue to contribute to climate warming, the overall impact becomes negative and will outweigh the

benefits of fertilization after only 10 years.

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Approximately 93% of crop losses throughout the rest of this century will be

caused by non–carbon dioxide emissions, the most damaging of these being methane. Even if the impact of surface ozone is taken out of the results, the non–carbon dioxide damage is still 9 times larger than that caused by carbon dioxide.

Finally, to see how policy and societal actions to mitigate pollutant emissions might affect crops, the author compared two future scenarios: one with low

emissions and another with high emissions. If strong emission mitigation techniques are implemented, the results show that crop yields will improve by

about 3% for reduced carbon dioxide, 5% for a reduction in hydrofluorocarbons, and 16% if methane is reduced. Under the high-emission scenario, crop yield losses will be about 25% greater by the end of the century, threatening global

agriculture. As the first study to look at the relative contributions of individual pollutants to climate change and crop yield losses, the findings here fill an important gap for

policy makers, who can limit specific pollutant emissions. The author suggests that policy makers should strengthen efforts to reduce methane and

hydrofluorocarbons in the atmosphere to help prevent severe crop loss by the end of the century.

What do you mean by Ozone layer depletion?

Ozone Layer depletion:

Ozone layer depletion, is simply the wearing out (reduction) of the amount of

ozone in the stratosphere. Like pollution, Ozone depletion has been pinned down to one major human activity. Industries that manufacture things like insulating foams, solvents, soaps, cooling

things like Air Conditioners, Refrigerators and „Take-Away‟ containers use chlorofluorocarbons (CFCs). These substances are heavier than air, but over time, (2-5years) they are carried high into the stratosphere by wind action.

Depletion begins when CFC‟s get into the stratosphere. Ultra violet radiation from the sun breaks up these CFCs. The breaking up action releases Chlorine atoms.

Chlorine atoms react with Ozone, starting a chemical cycle that destroys the good ozone in that area. One chlorine atom can break apart more than 100,000 ozone molecules

Discuss the causes of ozone layer depletion. 4(13)

Describe the causes of ozone layer depletion. 4(15)

Causes of ozone layer depletion:

1. Chlorofluorocarbons (CFC): Ozone depletion occurs when the natural balance between the production and

destruction of stratospheric ozone is disturbed. Although natural phenomenon can cause ozone depletion but human activities such as CFCs are now accepted as major cause of depletion. All ozone depleting chemicals contain chlorine and

bromine. CFCs are highly volatile and non-combustible so they are very quickly evaporated and can easily reach in stratosphere where ozone is present here they

start depleting ozone molecules. These CFCs have also adverse effects on human health. It leads to 80% of total ozone layer depletion. 2. Unregulated lunches of rockets:

Another major cause of large scale ozone depletion is Rocket launches. It has been studied that unregulated rocket launches can result in much more ozone

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depletion than CFCs. It is estimated that if rocket launches will be let

unregulated then it would cause huge ozone loss by the year 2050 than the CFCs have done. 3. Global warming:

Global warming also leads to ozone layer depletion. Due to global warming and greenhouse effect most of the heat is trapped in troposphere which is the layer below the stratosphere. As we all know ozone is present in stratosphere so heat

don‟t reaches troposphere and it remain cold as recovery of ozone layer requires maximum sunlight and heat so it leads to depletion of ozone layer.

4. Nitrogenous compound: Nitrogenous Compounds emitted by human activities in small amount like NO, N2O and NO2 are considered to be greatly responsible for the depletion of ozone

layer.

Briefly describe the effects of ozone layer depletion on organism.

Effect of Ozone depletion on organism:

i. The 3 kinds of skin cancer -Basal cell carcinoma, squamass cell carcinoma and melanoma are rapidly climbing the list of human diseases caused by

UV- rays ii. UV- radiations cause blood vessels near the skin surface to carry more blood

making the skin hot , swollen or red causing sunburn

iii. UV radiation is also absorbed by cornea & lens in the eye leading to photokeratitis & cataracts.

iv. Ozone at low concentration is also known to cause accumulation of inflammatory cells at the site of lung injury causing severe damage to lung

v. Many microphytoplanktons would die because of their exposure to UV solar

radiation. vi. The marked reduction in the productivity of phytoplanktons would in return

adversely affect zooplankton. The marine animals, fishes etc. will starve in

the absence of sufficient supply of food vii. The loss of fish population would directly affect the inhabitants of coastal

areas viii. The increased UV radiation will increase the mortality rate of larvae of

zooplanktons

ix. Exposure to air containing ozone results in the lesions to plants usually confined to the upper surfaces of leaves

x. Ozone flecking is observed with the plants of grape, citrus & tobacco at 0.02

ppm, it damages tomato, pea & other plants. In pine seedlings, it cause tip burn

xi. Plant proteins are susceptible to UV injury. About 20-50% chlorophyll reduction & harmful mutation have also be observed.

xii. In USA & California, fruits & vegetables yields have reduced due to ozone

pollution. Grapes are no longer produced mainly because of ozone pollution. xiii. Ozone along with other pollutants like SO2 & NO2 is affecting crop loss

How CFCs destroy ozone layer?

Write down the Mechanism of ozone layer depletion by CFCs

Mechanism of ozone layer depletion by CFCs:

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Write down the function of ozone layer.

Function of ozone layer:

Presence of ozone layer in the stratosphere is of vital significance for all biota

because the harmful solar radiations such as Ultraviolet-rays which are lethal to life on the earth aren't allowed to enter the earth‟s atmosphere by ozone layer. In

the absence of this layer, the ultraviolet rays of the sun will reach the earth surface and consequently the temperature of the lower atmosphere will rise. Thus, the ozone layer strongly absorbs or blocks of short waved ionizing

ultraviolet rays and so protects the life on earth from severe radiation damage.

What do you mean by weather & climate? 2(14)

Weather:

The state of the atmosphere changes from time to time and its conditions at any particular time is called the weather

Weather is the day to day state of atmospheric condition at any place.

Climate:

The state of the atmosphere over a period of time (20-30 years) is known as climate.

Climate is an average weather condition of a locality for a long period of time.

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Describe the impact of climate change on agriculture.

Impact of climate change on agriculture: i. The climate change may reduce average crop yields & may lead to decrease yield

stability. However, some plants may increase photosynthesis at higher temperature & CO2 but all plants will not be benefited.

ii. The total amount of global rainfall will increase, although there will be regions that may receive less rainfall than before. The El-Nino effect, which invades world‟s oceans & continents every decade, is suggested to get a big boost by the

rise in temperature of the atmosphere iii. Demand for irrigation is likely to increase in all regions. It will lead to higher

competition for existing water resources. Increase in temperature may also result in higher amount of evapotranspiration which may lead to increase frequency of droughts & demand for irrigation.

iv. Ranges & populations of agricultural pest currently limited by temperature may change. Higher temperature may increase diseases & heat stress. Some livestock diseases that are limited to tropical countries at present such as

African swine fever may spread causing serious economic losses v. Sea levels will rise by about 18 cm by 2040 & by 48 cm by 2100 attributed

mainly due to thermal expansion of water & melting of glaciers. Although this sea rise may look small, there are countries such as Bangladesh, Maldives etc. where much of the population currently live on the land that would be flooded

by a sea level rise of just about 50 cm. Sea level rise could also affect fisheries directly & indirectly through the availability of feed

vi. Alteration of the energy balance & circulation system in the world ocean will directly affect the productivity of the marine ecosystem.

Increase in temperature is likely to affect the crop calendars in low latitude

regions particularly where more than one crop in harvested in a year.

Describe the factors affecting the climate. 8(14)

Factors affecting climate:

There are several factors which affect the climate. These are as follows- 1. Latitude:

Temperature range increases with distance from the equator. Also, temperatures decrease as you move away from the equator. This is because the suns rays are dispersed over a larger area of land as you move away from the equator. This is

due to the curved surface of the Earth and the difference in the concentration of solar energy at the equator and the poles. In addition, Polar Regions are colder because the suns rays have further to travel compared to places on the equator.

2. Altitude: Temperatures decrease with height. The air is less dense and cannot hold heat as

easily. Temperature usually decreases by 1°C for every 100 metres in altitude. 3. Winds: If winds have been blown from a hot area they will raise temperatures. If winds

have been blown from cold areas they will lower temperatures. 4. Distance from the sea (continentality):

Land heats and cools faster than the sea. Therefore coastal areas have a lower temperature range than those areas inland. On the coast winters are mild and summers are cool. In inland areas, temperatures are high in the summer and

cold in the winter.

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5. Aspect: Slopes facing the sun are warmer than those that are not. Therefore, south-facing slopes in the northern hemisphere are usually warm. However, slopes

facing north in the southern hemisphere are warmest.

Difference between climatology & meteorology 1.5(14)

Difference between Weather & Climate:

Weather / Meteorology Climate / Climatology

i. Weather is the day to day state of

atmospheric condition at any place

i. Climate is an average weather

condition of a locality for a long period of time.

ii. It does not affect the distribution of natural vegetation

ii. It has a great influence on the distribution of natural vegetation

iii. Weather affects the daily work such as land preparation, planning,

seeding etc.

iii. Climate affects the growing of crops

iv. Weather has a great influence on

sunshine hours

iv. Climate has a great influence on

day length

v. It has no influence on soil

formation

v. It has definite influence on soil

formation

vi. Yield discrepancies occur

sometimes due to difference of weather

vi. It controls the distribution of

vegetation.

Write down the consequences of global warming on the people living the coastal areas. 6(15)

The Effect of Global warming on people living coastal area:

Climate change can affect coastal areas in a variety of ways. Coasts are sensitive to sea level rise, changes in the frequency and intensity of storms, increases in

precipitation, and warmer ocean temperatures. In addition, rising atmospheric concentrations of carbon dioxide (CO2) are causing the oceans to absorb more of the gas and become more acidic. This rising acidity can have significant impacts

on coastal and marine ecosystems. The impacts of climate change are likely to worsen problems that coastal areas already face. Confronting existing challenges that affect man-made infrastructure

and coastal ecosystems, such as shoreline erosion, coastal flooding, and water pollution is already a concern in many areas. Addressing the additional stress of

climate change may require new approaches to managing land, water, waste, and ecosystems.

Write down the present status of CO2 in atmosphere

Present status of CO2 in atmosphere:

Global annual mean CO2 concentration has increased by more than 45% since the start of the Industrial Revolution, from 280 ppm during the 10,000 years up

to the mid-18th century to 410 ppm as of mid-2018. The present concentration is the highest in the last 800,000 and possibly even the last 20 million years. The

increase has been caused by human activities , particularly the burning of fossil fuels and deforestation .This increase of CO2 and other long-lived greenhouse

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gases in Earth's atmosphere has produced the current episode of global warming.

About 30–40% of the CO 2 released by humans into the atmosphere dissolves into oceans, rivers and lakes. As of April 2018, the average monthly level of CO2 in Earth's atmosphere

exceeded 410 parts per million. The daily average concentration of atmospheric CO2 exceeded 400 ppm on 10 May 2013 although this concentration had already been reached in the Arctic in June 2012. It currently constitutes about 0.041%

by volume of the atmosphere, (equal to 410 ppm).The amount of CO2 will be 700 ppm by 2050.

What are CFCs? Write down the uses of CFCs

CFCs:

CFCs are short form of the compound, chlorofluorocarbon, which contains

carbon, chlorine, and fluorine. Chlorofluorocarbons are more commonly referred to as CFCs or, when used for refrigeration, CFCs are also known as Freon. Developed in the 1930s as a safe alternative to ammonia, usage of CFCs grew

rapidly because of its usefulness, low toxicity, non-inflammability, least chemical activity and easy to handle, stable on earth, inexpensive and convenience

throughout most of the 20th century. Over the past forty years, manufacturing of CFCs has been heavily regulated and phased out due to the harmful impact it has on the ozone layer.

Uses of CFCs:

i. Due to their chemical properties, CFCs became useful as coolants and propellants.

ii. More commonly known as Freon for refrigeration, CFCs are used extensively

in appliances as a safe method of refrigeration. iii. Used as a propellant for aerosol cans.

iv. Some of the common uses were hairspray, spray paint and cooking spray. v. Used in cleaning solvent vi. It is used as sterilizing chemicals for surgical instrument and in medicinal

and oral inhalation. vii. Also used in computer, plastic foams.

Short notes:

Global warming 2.5(14) (From Above)

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