bro many successful aspirants have suggested the books by foreign authors. Mohammad Bin Ashraf topper 2009 has also suggested to study deblij and strhaler..... if u want to get good scores always study standard books.... quality matters

lolzz.. yes it is.... buy human geography 6th edition by deblij and physical geography by strahler(any edition).... both are very good books and for Pakistan geography u wont find any foreign author so buy Pakistan geography by fazal kareem.. these are the books am using and found them worthy... gOOd Luck

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Don't judge my path... for you haven't walked my journey...

yes perhaps you are right jiashah. toppers have recommended foriegn authors books. but my dear if some one can prepare the same question in a better way from locally available books and get good marks,then what will you say?

dear i know quality matters,but we dont want to show them we are true geographers.

yousafzaii, bro honestly speaking i read alot of foriegn authors books and at the end of the day in examination hall i was unable to reproduce that difficult language, what i did? i simply reply all of my question the way i understood them.

i got very good marks in my masters in physical geo. paper 74/75.


bro in css exams with quality, your technique of answering the question matters alot. if you can answer the question in a different style with simple language,it will definetly give you good marks.

examiner will check your understanding of the question and you briliantly you replied it.

plz i have no offence againts any one. i am just giving my own advise to yousafzaii. if hurt anyone feeling then forget it.

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GEO to aise k sab tumhara ha,MARO to aisa jaise tmhara kuch bhi nhi.

Maza deti han zindagi ki thokerin unko,jinhen NAAM-E-KHUDA le kar sanbhal janey ki adat ho.

i really appreciate ur replay and i think its just an ongoing discussion so o none is suppose to hurt...

as far as ur views about the foreign authors are concerned you are not the only one as i have seen seniors recommending local books and even hammad haider of officers acadmy reccomended fazal karim khan for geo 2...plus i heard that the book of bajwa is some how copy of foreign authors ( correct me if m wrong )...

okay SABAHT now plz give me some tips how to start making notes of ppr 1...kis cahpter say start karo...and the notes u have been posting are complete notes or some sort of outlines..??? and u r using internet or some book or notes for them...

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He,who lives upon hope
Will soon die fasting...

salam to all. good you get my point lol, yes you are right some of these books are copies of foriegn books.


now come to main point dear yousafzaii,my notes are complete notes with heading and if you want to add in them you can to make them different,i have tried my level best to provide complete information of all topics and where only some information is required i have just pasted diagrames.ohhhhhh... dont ask the sorce pages kam ho ga aur sources bohat zyada.


ok now i am going to tell you step by step how to prepare geo.1 notes by yourself,

the 1st chapter is all about solar system and introduction of some geographical terms, you just need to learn their definitions and important facts bcoz this chapter is important for objective.

now come 2nd chapter about atmosphere is again impo. for objective,abhi tak is chapter ma sa kuch aya to nhi but structure prepare ker lo.

now come 3rd chapter about insolation and temperature,very important chapter regarding objective and subjective.

next chapter is of pressure and winds, very very important specially subjective point of view. objective bhi bohat atta ha is ma sa.

baqi ma apko baad ma batate hun,

pehle yahan taq prepare karo. if you find any difficuty ur welcome to ask any time, but i will reply when i got time

__________________
GEO to aise k sab tumhara ha,MARO to aisa jaise tmhara kuch bhi nhi.

Maza deti han zindagi ki thokerin unko,jinhen NAAM-E-KHUDA le kar sanbhal janey ki adat ho.

Syeda is doing good job but her notes are for advance level. Emporiums n Jahangir's geo books are sufficient. We are not supposed to do M.phil in Geography.

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Try not to become a man of success but a man of value.

i really like the way u tried to convince yousafzai to use local authors books... in fact i don't have experience of css exam so i am just unable to say anything about examination hall... but as far as my academic career and experience is concerned i always tried to clear concepts and for that no local author helps u...... for geography i have't seen any local author's book so i would not comment on the quality. yeah one thing for sure crammers really collapse in the examination hall because u never see any question that simple and easy in the question paper as u prepare from book.. thing is not to reproduce the DIFFICULT WORDS but it is to reproduce CONCEPTS and IDEAS....... i suggested what i felt the best, choice is always yours
i wish u all, very best of luck

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Don't judge my path... for you haven't walked my journey...

Yeah,Arthur Strahler,name says it all.

first of all @ candidguy thanks for your support.
@aariz i didnot mean that.i am just providing you notes from every angle so that if question come you can easily tacle it. remember i am providing you even those information which are latest observed in 2010 and they are not found in any book available in market.anyway your comments are always welcome.


@ dear jiashah i am not here to convince anyone,i just tell him the facts,and my experience so that he can make his own decision.being a teacher i also insist on the clarity of concepts,but dear you didinot understand what i said is if those concepts are in a difficult language and obviously your concepts are clear but at the end of the you will prefer easy thing on difficult one.

well dear i didnot get you point of cramming?that unfair even in examination hall most brilliant students also forget most of the things then you cannot call everyone crammer.

at last i think there is no use to disscuss bcoz the final decision is in yousaf hand whatever book he like he will buy.

i also want to wish you best of luck and score good marks.i will be 1st who will be happy more than anyone else.

yaro ab bas karo muje notes bhi to paste karne han.

i am very friendly to agar ma koi baat ker dun to just igore it, ma zara thori naughty hun.

__________________
GEO to aise k sab tumhara ha,MARO to aisa jaise tmhara kuch bhi nhi.

Maza deti han zindagi ki thokerin unko,jinhen NAAM-E-KHUDA le kar sanbhal janey ki adat ho.

TOPIC NO:-3

ELEMENTS OF WEATHER AND CLIMATE


The Atmosphere

Our atmosphere is a dynamic mixture of gases that envelop the Earth. Two gases, nitrogen and oxygen, make up most of the atmosphere by volume. They are indeed important for maintaining life and driving a number of processes near the surface of the Earth. Many of the so called "minor gases" (known here as "variable gases") play an equally important role in the Earth system. These gases include those that have a significant impact on the heat budget and the availability of moisture across the Earth. The atmosphere is not a homogeneous mass of gases, but has a layered structure as defined by vertical temperature changes.

Atmospheric Structure

If we examine the vertical structure the atmosphere in different places we will find it varies in height, being lowest at the poles and highest at the equator. The varying height is due to the spatial variation in heating of the Earth's surface and thus the atmosphere above. This fact makes it difficult to define exact heights for the layers of the atmosphere. The solution is to subdivide the atmosphere not on the basis of fixed heights, but on temperature change. Figure illustrates the way in which the atmosphere is divided using temperature change as the primary criterion.


Troposphere and Tropopause

The troposphere is the layer closest to the Earth's surface. The graph of temperature change indicates that air temperature decreases with an increase in altitude through this layer. Air temperature normally decreases with height above the surface because the primary source of heating for the air is the Earth. The rate of change in temperature with altitude is called the environmental lapse rate of temperature (ELR) The ELR varies from day-to-day at a place, and from place to place on any given day. The normal lapse rate of temperature is the average value of the ELR, .65o C /100 meters. That is, at any particular place and on any given day the actual ELR may be larger or smaller, but on average has a value of .65o C /100 m. So if I went outside today it could be .62o C /100 m and then tomorrow it might be .68o C /100 m. The ELR also varies from place - to - place on a given day. That is, at Chicago, Illinois it might be .65o C /100 m and on the same day it could be .62o C /100 m over London, England

Under the right conditions, the air temperature may actually increase with an increase in altitude above the Earth. When this occurs we are experiencing an inverted lapse rate of temperature, or simply an inversion. Shallow surface inversions are typical over the snow covered surfaces of subarctic and polar regions, and sometimes occur when high pressure cells inhabit a region.

The tropopause lies above the troposphere. Here the temperature tends to stay the same with increasing height. The tropopause acts as a "lid" on the troposphere preventing air from rising upwards into the stratosphere.

Stratosphere

Above the tropopause lies the stratosphere. Note in Figure that the temperature of the air does not change with an increase in elevation. If a layer of air exhibits no change in temperature with an increase in elevation we typically refer to it as an isothermal layer i.e. layer of equal temperature. Through most of the stratosphere the air temperature increases with an increase in elevation creating a temperature inversion. The inverted lapse rate of temperature is due to the presence of stratospheric ozone which is a good absorber of ultra-violet radiation emitted by the Sun. As energy penetrates downward, less and less is available for lower layers and hence the temperature decreases toward the bottom of the stratosphere. The downward reduction of heat transfer due to solar energy absorption from above is offset by the heat given off by the Earth creating the isothermal layer at the bottom of the stratosphere. At the top of the stratosphere lies the stratopause. Like the tropopause, the stratopause is an isothermal layer that separates the stratosphere from the mesosphere


Mesosphere and beyond

It is the properties of the previously discussed layers that affects most of what we study in physical geography. Processes acting in layers above the stratopause have relatively little impact on our elemental study of Earth near-surface processes. In the mesosphere air temperatures begin to decrease with increasing altitude. 99.9 percent of the gases that comprise the atmosphere lie below this level. The air of the mesosphere is thus extremely thin and air pressure very small. With very few molecules like ozone capable of absorbing solar radiation, especially near the top of the layer, the air temperature decreases with height. The mesopause separates the mesosphere from the thermosphere above.
Figure shows air temperature increasing with increasing altitude in the thermosphere. Here, energetic oxygen molecules absorb incoming solar radiation raising the layer's temperature. Because solar activity determines the temperature of the layer, temperature at the top of the layer is warmer than that near the bottom of the thermosphere. Even though the temperatures are quite high in the thermosphere, the heat content of the layer is very low due the low density of air at this level.

Functional layers

Two layers, the ionosphere and ozonosphere are identified when using function as the criterion for subdivision. The ionosphere is not really a layer of the atmosphere, but an electrified field of ions and free electrons. The ionosphere absorbs cosmic rays, gamma rays, X-rays, and shorter wavelengths of ultraviolet radiation. The spectacular display of auroral lights is generally found in this region.

The ozonosphere, also called the "ozone layer", is the concentrated layer of ozone found in the stratosphere. Ozone (O3) absorbs ultraviolet light between 0.1 - 0.3µm. The ozone layer absorbs 97 - 99% of the Sun's ultraviolet light that can be harmful to life on earth. Though relatively constant through millions of years, seasonal fluctuations of ozone especially over the Arctic and Antarctic are common. The ozone layer is thinner at the equator and thicker at the poles. Ozone concentrations are highest in the spring and generally lowest during the autumn.



CSS Forums - View Single Post - Diagrams Related to Physical Geography



PROBLEMS OF ATMOSPHERE


1) The Greenhouse effect

The earth is surrounded by a blanket of gases. This blanket traps energy in the atmosphere, much the same way as glass traps heat inside a greenhouse. This results in an build up of energy, and the overall warming of the atmosphere. The greenhouse effect is a natural process which made life on Earth possible. Without naturally occurring greenhouse gases such as water vapour, carbon dioxide, methane and nitrous oxide, the Earth's surface temperature would be 33°C cooler, a chilly -18°C rather than the tolerable 15°C.

When we talk about the greenhouse effect we mean the ENHANCED effect which is caused by the increase of greenhouse gases from human sources. Since the beginning of industrialization, 200 years ago, concentrations of these gases have increased . It is estimated that the Earth's average temperature has risen by 0.6°C since 1880 because of emissions of greenhouse gases from human activity

The main sources of these emissions, particularly carbon dioxide, methane and nitrous oxide, are:

*the combustion of large amounts of fossil fuels (producing CO2)
*deforestation (less trees mean that less CO2 is being mopped up)


A increase in global temperatures may seem great, you might even think of 'Costa del Blackpool'. Unfortunately global warming will probably result in big swings in weather patterns across the world. Summers will become dryer and hotter, Winters will be wetter and colder. Other things will start to happen:

*Thermal expansion of the water and melting of continental glaciers would cause sea levels to rise, possibly as much as two feet, by the end of next century.
*Rising temperatures could lead to changes in regional wind systems which would influence global rainfall distribution and lead to the redistribution and frequency of floods, droughts and forest fires.
*Increased sea temperatures would cause the destruction of coral reefs around the world.
*Climate change would create favourable conditions for growth in insect populations. This would likely have a bad effect on agriculture and human health and result in a spread of malaria and other tropical diseases.
*Water supplies would become disrupted and droughts would be more common .


2) Damage to the ozone layer

Ozone is oxygen that contains molecules that have 3 oxygen atoms (O3). The molecule is triatomic instead of the usual O2 molecule which is diatomic. There is a layer of ozone high up in the atmosphere which shields the Earth from the sun's harmful UV rays, these rays can lead to an increase in skin cancer. The ozone is present in very small quantities but it is enough to absorb the UV rays preventing them reaching the surface.

Scientists began to investigate the ozone layer in the 1970's, it wasn't until the mid 1980's that alarm bells started to ring. Concentrations of ozone appeared to be dropping in certain areas of the world (the layer was starting to thin-out). The cause of this reduction was thought to be man-made. The images below highlight the Ozone depletion over the Southern Hemisphere 1980-1991:-
In 1985 over 60 countries pledged to phased out a group of chemicals called CFC's. These very stable chemicals were once widely used in aerosols and refrigerators. It was thought that their release into the atmosphere produced chlorine radicals which reacted with O3 to produce O2. The emission of CFC's into the environment is now greatly reduced, unfortunately the damage has already been done and the CFC molecules, thanks to their stability, are still causing ozone depletion.



3) Acid rain

Rain water is naturally acidic due to carbon dioxide which partially reacts with water to give carbonic acid (H2O + CO2 -> H2CO3). When we talk about acid rain we mean the ENHANCED effect which is caused by other gases released when fossil fuels are burnt. Two gases are the main culprits:

*Sulphur dioxide - Fossil fuels often contain a lot of sulphur impurities which burn to give sulphur dioxide. The SO2 reacts with water in the atmosphere to from a weak solution of sulphuric acid.

*Nitrogen oxides - Under normal conditions nitrogen and oxygen don't react together. At very high temperatures (in an engine) a small proportion of oxygen reacts with nitrogen to give nitrogen oxides. These oxides react with water in the atmosphere to from a weak solution of nitric acid acid.

The dilute acid falls to ground as acid rain which causes the following problems:
*Lakes become acidic and plants and fishes die as a result
*Tree growth is damaged, whole forests can die as a result
*Acid rain attacks metal structures and also buildings made of limestone.

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regards sabahat

__________________
GEO to aise k sab tumhara ha,MARO to aisa jaise tmhara kuch bhi nhi.

Maza deti han zindagi ki thokerin unko,jinhen NAAM-E-KHUDA le kar sanbhal janey ki adat ho.