Sunday, September 1, 2013

Arizona Concrete

ARIZONA CONCRETE












John McCollam

















Geology 101, Section 12262
Randy Porch
20 November 1996



ARIZONA CONCRETE
According to the Mine Faculty at the University of Arizona, cement is manufactured primarily from suitable limestone and shale rocks. Arizona had two dry-process cement plants in 1969, namely the Arizona Portland Cement Company plant in Pima County, near Tucson, and the American Cement Corporation plant at Clarkdale, in Yavapai County (52-53).
The use of cementing materials goes back to the ancient Egyptians and Romans, but the invention of modern portland cement is usually attributed to Joseph Aspdin, a builder in Leeds, England, who obtained a patent for it in 1824. Currently, the annual world production of portland cement is around 700 million metric tons (Danbury).
Many people use the words concrete and cement interchangeably, but they=re not. Concrete is to cement as a cake is to flour. Concrete is a mixture of ingredients that includes cement but contains other ingredients also (Day 6-7).
Portland cement is produced by pulverizing clinker consisting essentially of hydraulic calcium silicates along with some calcium aluminates and calcium aluminoferrites and usually containing one or more forms of calcium sulfate (gypsum) as an interground addition. Materials used in the manufacture of portland cement must contain appropriate proportions of calcium oxide, silica, alumina, and iron oxide components. During manufacture, analyses of all materials are made frequently to ensure a uniformly high quality cement.
Selected raw materials are crushed, milled, and proportioned in such a way that the resulting mixture has the desired chemical composition. The raw materials are generally a mixture of calcareous (calcium oxide) material, such as limestone, chalk or shells, and an argillaceous (silica and alumina) material such as clay, shale, or blast-furnace slag. Either a dry or a wet process is used. In the dry process, grinding and blending operations are done with dry materials. In the wet process, the grinding and blending are done with the materials in slurry form. In other respects, the dry and wet processes are very much alike.
After blending, the ground raw material is fed into the upper end of a kiln. The raw mix passes through the kiln at a rate controlled by the slope and rotational speed of the kiln. Burning fuel (powdered coal, oil, or gas) is forced into the lower end of the kiln where temperatures of 2600°F to 3000°F change the raw material chemically into cement clinker, grayish-black pellets about the size of 1/2-in.-diameter marbles.
The clinker is cooled and then pulverized. During this operation a small amount of gypsum is added to regulate the setting time of the cement. The clinker is ground so fine that nearly all of it passes through a No. 200 mesh (75 micron) sieve with 40,000 openings per square inch. This extremely fin gray powder is portland cement (Kosmatka and Panarese 12-15).
Dany Seymore of Show Low Ready Mix said that the cement used by Show Low Ready Mix is trucked in by Apex Freight Company and comes from the cement plant in Clarkdale, Arizona, now know as Phoenix Cement. Their aggregate comes from Brimhall Sand and Rock in Snowflake, Arizona. Show Low Ready Mix uses Fly Ash from the A.P.S. power plant just out side of Joseph City, Arizona, in their cement. The mixtures they use are as follows:
Silicia Dioxide Cement 21% Ash 62%
Aluminum Trioxide Cement 4% Ash 23%
Ferric Oxide Cement 3% Ash 6%
Calcium Oxide Cement 64% Ash 3.5%
Mag. Oxide Cement 2.5% Ash 1.2%
Sulfur Trioxide Cement 3% Ash .2%
These combine to make:
1. Tricalcium silicate C3S
2. Dicalcium silicate C2S
3. Tricalcium aluminate C3A
4. Tetracalcium aluminoferrite C4AF
1 and 2 make up 75% of cement. 1 and 2 plus H2O equal CSH (Calcium Silicate Hydrate) which is the glue. Fly Ash is C3S plus C2S which equals Calcium hydrazide which is a white stuff and water soluble. Calcium Hydrazide and Fly Ash equal CSH.
The winter and summer mixtures are different due to the weather conditions. For winter, Fly Ash is not used because it inhibits the set time of the concrete. Also used is accelerators to help the concrete set faster. A material called Fibermesh is used in the concrete for reinforcement and to control cracking as the concrete sets. Mr. Seymore also states that heat and moisture are the main components to make concrete set up.
The concrete is mixed out of the plant into the truck so the materials can be feathered together and mixed up properly. The PSI ratings are determined by the mixture of sand, aggregate, cement, water, and chemical additives that are mixed together. The most common mixtures for residential are 2500 to 3000 PSI.
Concrete cannot be delivered any where that is more than 90 minutes away from the batch plant, unless a chemical inhibiter is used to put the concrete to sleep until it reaches the sight of delivery. Then another chemical is added to activate the concrete.
Show Low Ready Mix mixes approximately 25,000 to 30,000 cubic yards of concrete in Show Low per year. That is only 70 to 75 percent of the total concrete poured in Show Low. There are a few other companies that also handle the Show Low area.
Concrete is basically a mixture of two components: aggregates and paste. The paste, comprised of Portland cement, (the term APortland cement@ pertains to a calcareous hydraulic cement produced by heating the oxides of silicon, calcium, aluminum, and iron.) Water binds the aggregates (sand and gravel or crushed stone) into a rocklike mass. The paste hardens because of the chemical reaction of the cement and water.
The paste is composed of Portland cement, water, and intrapped air or purposely entrained air. Cement paste ordinarily constitutes about 25% to 40% of the total volume of concrete. Since aggregates make up about 60% to 75% of the total volume of concrete, their selection is important. Aggregates should consist of particles with adequate strength and resistance to exposure conditions and should not contain materials that will cause deterioration of the concrete.
Aggregates are generally divided into two groups: fine and coarse. Fine aggregates consist of natural or manufactured sand with particle sizes ranging up to 3/8 inches; coarse aggregates are those with particles retained on the No.16 sieve and ranging up to 6 inches. The most commonly used maximum aggregate size is 3/4 inch or 1 inch. A continuous gradation of particle sizes is desirable for efficient use of the cement and water paste.
For any particular set of materials and conditions of curing, the quality of hardened concrete is determined by the amount of water used in relation to the amount of cement . Some advantages of reducing water content are: increased compressive and flexural strength, lower absorption, increased resistance to weathering, better bond between successive layers and between concrete and reinforcement, less volume change from wetting and drying, and reduced shrinkage cracking tendencies. The less water used, the better the quality of the concrete, provided it can be consolidated properly.
The freshly mixed (plastic) and hardened properties of concrete may be changed by adding admixtures to the concrete, usually in liquid form, during batching. Admixtures are commonly used to: adjust setting time or hardening, reduce water demand, increase workability, intentionally entrain air, and adjust other concrete properties (Kosmatka and Panarese 1-2).
After completion of proper proportioning, batching, mixing, placing, consolidating, finishing, and curing, hardened concrete becomes a strong, noncombustible, durable, abrasion-resistant, and practically impermeable building material that requires little or no maintenance. Concrete is also an excellent building material, because it can be formed into a wide variety of shapes, colors, and textures for use in almost unlimited number of applications.
Works Cited
ACement and concrete.@ The 1996 Grolier Multimedia Encyclopedia. CD-ROM. Danbury: Grolier, 1996.
Day, Richard. The Home Owner Handbook Of: Concrete and Masonry. New York: Bounty Books, No Copyright Date.
Kosmatka, Steven H., and William C. Panarese. Design and Control of Concrete Mixtures. Skokie, Ill.: Portland Cement Association, 1990.
Seymore, Dany. President of Show Low Ready Mix. Personal interview. 11 November 1996.
College of Mines Faculty, University of Arizona. Arizona: Its People and Resources. Tucson, AZ.: The University of Arizona Press, 1972.

Argentina

Argentina
By: Chris Ojeda


Argentina is a South American country with a population of thirty one million people. Argentina's capital is Buenos Aires, which is one of the largest cities in South America. Buenos Aires is situated on the coast of Argentina, which makes Buenos Aires a major trade route in Argentina and in South America. Argentina's national language is Spanish and the major religion is Roman Catholicism.
Argentina is a country with much natural beauty. It has miles of beautiful beaches and is also surrounded by the majestic Andes mountains. The Andes mountains are among the highest mountains in the world. Argentina's tallest mountain is the Cerro Aconcagua. This mountain reaches an amazing height of 22,200 ft. America's tallest mountain only reaches the height of 20,000 ft.
Argentina has a huge industrial and agricultural base. Argentina has a large amount of natural resources which includes copper, silver, coal, iron ore, uranium and petroleum. Argentina is the #1 copper producer in the world. Argentina also produces huge amounts of coal and is self sustained in petroleum products.
Argentina also grows much more food than it consumes. Its main crops include wheat, tobacco and cattle. Argentina ranks 3rd in the world among wheat exporters, right behind the United States and Canada. Argentina is also one of the largest tobacco exporters as well.
Argentina's large industrial and agricultural base makes it one of the richest countries in South America. With its rich history and its beautiful mountains and beaches, not to mention its wonderful Spanish culture, Argentina is a very special place to visit in South America.

Angina Pectoris

Tropical Africa: Food Production and the
Inquiry Model

Hunger is the result of disasters such as drought, floods, the
.changing of the jet stream patterns and other natural disasters
.They are beyond our control

It has been estimated that one third of the land in Tropical
Africa is potentially cultivable, though only about 6% of it is
,currently cultivated. However, to change farming from a low-input
low-yield pattern to a high-input, high-yield pattern necessitates
the use of more fertilizer and the planting of high-yielding
.varieties of crops

There are a number of environmental factors, related mostly to
.climate, soils and health, resisting easy developmental solutions
.Rainfall reliability is closely connected to rainfall quantity
The rainfall in the equatorial heart is very plentiful and
reliable. However, there is much less rainfall towards the outer
edges of the rain belt. Periodic and unpredictable droughts are a
.characteristic feature of these border zones
:There are three climatic zones in Tropical Africa
,1.a region of persistent rain at and near the Equator
2.a region on each side of this of summer rain and winter
drought, and
3.a region at the northern and southern edges afflicted by
.drought

All the climates listed in the previous paragraph are modified
in the eastern parts of Tropical Africa by the mountains and
.monsoons

The soils of Tropical Africa pose another problem. They are
unlike the soils of temperate areas. Soils are largely products of
their climates, and tropical soils are different from temperate
soils because the climate is different. Because of the great heat
,of the tropics tends to bake the soils, while on the other hand
the rainfall leaches them. The combined heat and moisture tend to
produce very deep soils because the surface rock is rapidly broken
down by chemical weathering. All this causes the food's rate of
growth to slow down or maybe even stop and as a result food
production won't even come close in catching up to the rate of
.population increase; therefore starvation and hunger is present
In the process of a flood and drought, the roots of trees are
shallow and virtually no nutrients are obtained from the soil. The
vegetation survives on its own humus waste, which is plentiful. If
the vegetation is cleared, then the source of humus is removed and
the natural infertility of the soils becomes obvious. As being
another factor, this will cause the soil to produce wasteful and
.useless products which in turn will decrease the production

To conclude this essay, the climates in Tropical Africa take
a big role as being factors that could endanger or destroy the
process of plantation. On the other hand, it could also bring good
.fortune if climatic regions are fairly good

Alstalia

Australia is the world's smallest continent and sixth-largest country. With proportionately more desert land than any other continent, Australia has a low population density. Lying completely in the Southern Hemisphere, Australia is bounded by the Indian Ocean on the west and south and by the Pacific Ocean on the east. These oceans merge on the north in the Arafura Sea between Australia and Indonesia and New Guinea, and on the south in the Bass Strait. The coastline length, estimated at 19,200 km (12,000 mi), is remarkably short for so large an area, a result of the relative lack of indentation. Major inlets other than the Gulf of CARPENTARIA and the GREAT AUSTRALIAN BIGHT are few.

A self-governing member of the Commonwealth of Nations, Australia celebrated its bicentennial in 1988z. It is a federation of five mainland states (NEW SOUTH WALES, QUEENSLAND, SOUTH AUSTRALIA, VICTORIA, WESTERN AUSTRALIA) and one island state (TASMANIA), as well as two territories (AUSTRALIAN CAPITAL TERRITORY, NORTHERN TERRITORY). The country's name derives from the Latin terra australis incognita, meaning "unknown southern land," which resulted from a confusion between Australia and Antarctica on early world maps.

In many ways Australia is unusual among continents. It lacks major relief features and has a high proportion of dry land. The continent's isolation from other landmasses accounts for its unique varieties of vegetation and animal life, and for the existence of a Paleolithic (Old Stone Age) culture among the Aborigines. Except for Antarctica, Australia was probably the last continent to be inhabited by humans and the last to be explored and settled by Europeans. It is the only continent comprising a single nation-state.

Dutch explorers first sighted Australia in the early 17th century. Capt. James COOK explored the east coast in 1770 and claimed the land for Great Britain. In 1778 the first settlement (SYDNEY) was founded at an excellent harbor on the southeast coast. British convicts played an important role in the territory's early history. The discovery of gold and other ores attracted immigrants, but Australia remained a primarily agricultural country until World War II.

Subsequent industrialization has been rapid, and today Australia ranks as one of the world's most economically developed countries, although vast areas of the interior, known as the Outback, remain all but uninhabited.

A trip through panama

Day 1:

We arrived at Omar Torrijos airport via American Airlines early in the afternoon. We purchased our required tourist cards (3 balboas, as US dollars are called in Panama) at the airport, then caught a taxi for the 18 mile ride to our downtown hotel. The ride in the battered, un-airconditioned car was rather expensive (30 balboas), but the driver spoke English and was very friendly. We arrived at the hotel and checked in. While my dad was checking in I bought a guidebook in the hotel lobby and read up on the history of Panama City. The original city was founded in 1519 by Pedro Arias Davila, known as Pedrarias the Cruel, because of his eradication of all but three of the local Indian tribes during his tenure in Panama. Davila used the city as a place to store Incan gold before it was shipped to Spain. The original city was sacked and burned in 1671 by a group of buccaneers led by Henry Morgan. The city was rebuilt within a year, this time on a peninsula 18 miles away and surrounded by a strong wall. This old Spanish city is now the in the middle downtown Panama City.
Panama City is an international melting pot and its eating choices range from American fast food to excellent internationall cuisine. Eager to begin our sightseeing, we grabbed lunch at a nearby McDonald's after checking in then caught a bus. The buses in Panama are a tourist attraction in themselves. They are brightly painted, hung with fringe, and have constantly blaring Salsa and Caracas music playing. They are cheap (50 cents a ride). but are very crowded. After asking several drivers "Donde va este autobus?" we finally found one going to the Plaza Independencia. This plaza is the main square of the colonial town and is bordered on one side by a cathedral with twin mother of pearl towers that took 108 years to complete. On two other sides it is bordered by the Archbishop's Palace, now a university and the Central Post Office. While in the old part of Panama City we also visited the Iglesia de San Jose and saw the Golden Aaltar. This altar was in the original Panama City and was saved from Henry Morgan's pirates by a monk who painted it black to disguise it. When we finished touring we returned to our hotel and then ate dinner at El Pez de Ora, one of the city' famous seafood restaurants.


Day 2:
We woke early and headed out for a morning of shopping at the Mercado Publico. I bought some jewelry and some small wooden figurines as souvenirs, but when I asked "Donde esta los sombreros de Panama?", the vendor told me Panama hats were made in Ecuador. The hat most commonly worn in Panama is the "pita", a narrow brimmed straw hat with black and white stripes. The most important phrases to remember when shopping in Panama are " Cuanto cuesta esta?" and " Acceptas tarjetas de credita?" After shopping we had Chinese food in one of the local restaurants.
After eating we went to visit Panama's most famous attraction, the Panama Canal. The Canal was completed in 1914, and is considered one of the greatest engineering feats in the world. We took a shuttle from our hotel to the canal and then went on a 90 minute train ride all the way across the isthmus along the canal. The railroad we were traveling on was built in 1855 to transport '49ers who were on their way to the California gold rush and was the first "trans-continental" rail link. At one of the train stations we got off and walked to the Miraflores Locks, sat on bleachers, and watched the ships go through the canal. After our tour of the Panama Canal we returned to our hotel to get ready for a night of dinner and theater. We ate dinner at an Italian restaurant then went to the Teatro National for a performance of the Folkloric Ballet. The Folkloric Ballet features native folk dances and costumes and was very entertaining.

Day 3:
We rented a car and left Panama City headed southwest along the Pan American Highway. First we visited the Parque Natural Metropolitana, a zoo on the outskirts of Panama with monkeys, deer, sloths, and iguanas. We then drove toward El Valle, about 75 miles away. El Valle is located in the center of a dormant volcano. There we saw hot springs, botanical gardens (with square trees which scientists have been unable to explain!), and golden frogs found nowhere else on earth. We continued down the highway passing through the towns of Penonome, the geographic center of Panama, and Nata, on of the oldest towns in Latin America. The Interior of Panama is mostly farmland and grazing land for cattle. We even saw some cowboys! At night we arrived at Baquette, a village on the side of the dormant Baru Volcano, where we spent the night.

Day 4:
We began our day by visiting Volcan Baru National Park and taking a short hike to see the beautiful plants and birds. The volcano is the highest point in Panama at 3475 meters. After our hike we ate lunch and then drove to Chiriqui Grande where we dropped off our car. We then caught a ferry to Bocas del Toro where we visited Bastimentos National Park. The park has pristine white sand beaches where sea turtles nest. The coral reefs off the coast are home to more than 200 species of tropical fish. While there we also got to visit caves containing the largest population of fruit eating bats in the world! Later we went snorkeling of the coast of Almirante Island where we spent the night.

Thursday, April 4, 2013

Mozambique




The country I have picked for my project is Mozambique in south Africa, and is

located near Zimbabwe, Namibia,

Its climate in January consists of a rainy season. The rains last for about 190 days in

the north but only 120 days in the south. In the cool season may to august temperatures

range from 16 deg c to 27 deg c (that is 60 dea to 80 dea F). In the hot season august to

November temperatures range 28 deg c to 32 deg c (85 deg f to 90 deg f ).



The country has a wealth of mineral resources , especially copper ,lead, zinc , and coal .

Copper accounts for more than 80% of this countries export earnings. The copperbelt

where four large copper mines and several smaller mines are located is where most

mining takes place it lies north of lusaka along the Zairian border . The many rivers near

the mines have valuable potential for hydroelectric power.

Its population is mostly black Africans who speak BANTU. The national language is

english. Most people are Christians, traditional local baliefs still have a strong hold on

the

village people. Also witchcraft and old customs such as marrying several wives and

paying the parents for a bride are slowly dying out in the towns. most children attend

elementary school. but only a fifth of them go to high school. It only has one university

which was founded in 1965.

Corn is the main food .Also a favorite dish is nshima, a thick porridge made from corn.



Facts about the country

People

Population : 8.745,284 m density: 12 persons per sq km.

Distribution: 43% urban , 57% rural.

Official language: English

Major religions: traditional, roman, Catholicism, and protestian.

Education

Literacy: 81% of adult population.

Universities: 1

Life expectancy: women-59 men-55.

Government

Type:republic.

Government leader: Fredrick Chiluba.

Legislature: National Assembly.

Political subdivisions: nine provinces.

Communications

Railroads: 2164 kms total

Roads: 37359 kms total

Major airports: 1

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Wednesday, March 13, 2013

GLOBE : LATITUDES AND LONGITUDES

Globes may be of varying size and type – big ones,
which cannot be carried easily, small pocket globes,
and globe-like balloons, which can be inflated and are
handy and carried with ease. The globe is not fixed. It
can be rotated the same way as a top spin or a potter’s
wheel is rotated. On the globe, countries, continents
and oceans are shown in their correct size.
It is difficult to describe the location of a point on a
sphere like the earth. Now the question arises as to
how to locate a place on it? We need certain points of
reference and lines to find out the location of places.
You will notice that a needle is fixed through the
globe in a tilted manner, which is called its
axis
. Two
points on the globe through which the needle passes
are two poles – North Pole and South Pole. The globe
can be moved around this needle from west to east
just as the earth moves. But, remember there is a major
difference. The real earth has no such needle. It moves
around its axis, which is an imaginary line.
Another imaginary line running on the globe divides
it into two equal parts. This line is known as the
equator
. The northern half of the earth is known as
the Northern Hemisphere and the southern half is
known as the Southern Hemisphere. They are both
equal halves. Therefore, the equator is an
imaginary circular line and is a very
important reference point to locate places
on the earth. All parallel circles from the
equator up to the poles are called
parallels
of latitudes
. Latitudes are measured in
degrees.

The equator represents the zero degree
latitude. Since the distance from the
equator to either of the poles is one-fourth
of a circle round the earth, it will measure
¼
th of 360 degrees, i.e. 90°. Thus, 90
degrees north latitude marks the North
Pole and 90 degrees south latitude marks
the South Pole.

As such, all parallels north of the
equator are called ‘north latitudes.’
Similarly all parallels south of the equator are called
‘south latitudes.’
The value of each latitude is, therefore, followed by
either the word north or south. Generally, this is
indicated by the letter ‘N’ or ‘S’. For example, both
Chandrapur in Maharashtra (India) and Belo
Horizonte in Brazil (South America) are located on
parallels of about 20° latitude. But the former is 20°
north of the equator and the latter is 20° south of it.
We, therefore, say that Chandrapur is
situated at 20° N latitude and Belo
Horizonte is situated at 20° S latitude.
We see in Figure 2.2 that as we move
away from the equator, the size of the
parallels of latitude decreases.



I
MPORTANT PARALLELS OF LATITUDES
Besides the equator (0°), the North Pole
(90°N) and the South Pole (90° S), there
are four important parallels of latitudes–
(i)
Tropic of Cancer (23½° N) in the
Northern Hemisphere. (ii)
Tropic of
Capricorn
(23½° S) in the Southern
Hemisphere. (iii)
Arctic Circle at 66½°
north of the equator. (iv)
AntarcticCircle
at 66½° south of the equator.

H
EAT ZONES OF THE EARTH
The mid-day sun is exactly overhead at
least once a year on all latitudes in
between the Tropic of Cancer and the
Tropic of Capricorn. This area, therefore,
receives the maximum heat and is called
the
Torrid Zone.
The mid-day sun never shines
overhead on any latitude beyond the
Tropic of Cancer and the Tropic of
Capricorn. The angle of the sun’s rays
goes on decreasing towards the poles. As
such, the areas bounded by the Tropic
of Cancer and the Arctic Circle in the
Northern Hemisphere, and the Tropic of
Capricorn and the Antarctic Circle in the
Southern Hemisphere, have moderate
temperatures. These are, therefore, called
Temperate Zones
.
Areas lying between the Arctic Circle
and the North Pole in the Northern
Hemisphere and the Antarctic Circle and
the South Pole in the Southern
Hemisphere, are very cold. It is because
here the sun does not rise much above
the horizon. Therefore, its rays are
always slanting. These are, therefore,
called
Frigid Zones.
W
HAT ARE LONGITUDES?
To fix the position of a place, it is
necessary to know something more
than the latitude of that place. You
can see, for example, that Hyderabad
(in Pakistan) and Allahabad (in India)
are situated on the same latitude (i.e.,
25°25
'N). Now, in order to locate them
precisely, we must find out how far
east or west these places are from a
given line of reference running from
the North Pole to the South Pole.
These lines of references are called the
distances between them are measured in ‘degrees of
longitude.’ Each degree is further divided into minutes,
and minutes into seconds. They are semi-circles and
the distance between them decreases steadily polewards
until it becomes zero at the poles, where all the
meridians meet.
meridians of longitude, and the

Sunday, March 3, 2013

INDIA : CLIMATE, VEGETATION AND WILDLIFE

You read in newspapers daily and watch on T.V. or
hear others talking about weather. You must know
that weather is about day to day changes in the
atmosphere. It includes changes in temperature,
rainfall and sunshine etc. For example, as such it may
be hot or cold; sunny or cloudy; windy or calm. You
must have noticed that when it is hot continued for
several days you don’t need any warm clothing. You
also like to eat or drink cold things. In contrast there
are days together, you feel cold without woollen clothes
when it is very windy and chilly, you would like to
have something hot to eat.
Broadly, the major seasons recognised in India are:
• Cold Weather Season (Winter) December to
February
• Hot Weather Season (Summer) March to May
• Southwest Monsoon Season (Rainy)
June to September
• Season of Retreating Monsoon (Autumn) October
and November

COLD WEATHER SEASON OR WINTER


During the winter season, cool, dry winds blow from
north to the south. The sun rays do not fall directly in
the region as a result, the temperatures are quite low
in northern India.

HOT WEATHER SEASON OR SUMMER

In the hot weather season sun rays more or less directly
fall in this region. Temperature becomes very high.
Hot and dry winds called loo, blow during the day.



SOUTH WEST MONSOON SEASON OR RAINY SEASON

This season is marked by the onset and advance of
monsoon. The winds blow from Arabian Sea and Bay
of Bengal towards the land. They carry moisture with
them. When these winds strike the mountain barriers,
rainfall occurs.

SEASON OF RETREATING MONSOONS OR AUTUMN

Winds move back from the mainland to the Bay of
Bengal. This is the season of the retreating monsoons.
The southern parts of India, particularly Tamil Nadu
and Andhra Pradesh receive rainfall in this season.
However, the climate is about the average weather
condition, which have been measured over many years.
The climate of India has broadly been described as
Monsoon type. Monsoon is taken from the Arabic word
‘mausim’, which means seasons. Due to India’s location
in the tropical region, most of the rain is brought by
monsoon winds. Agriculture in India is dependent on
rains. Good monsoons mean adequate rain and a
bountiful crop.



The climate of a place is affected by its location,
altitude, distance from the sea, and relief. Therefore,
we experience regional differences in the climate of
India. Jaisalmer and Bikaner in the desert of Rajasthan
are very hot, while Drass and Kargil in Jammu and
Kashmir are freezing cold. Coastal places like Mumbai
and Kolkata experience moderate climate. They are
neither too hot nor too cold. Being on the
coast, these places are very humid.
Mawsynram in Meghalaya receives the
world’s highest rainfall, while in a
particular year it might not rain at all in
Jaisalmer in Rajasthan.

NATURAL VEGETATION

We see a variety of plant life in our
surroundings. How nice it is to play in a
field with green grasses. There are also
small plants called bushes and shrubs like
cactus and flowering plants etc. Besides
there are many tall trees some with many
branches and leaves like neem, mango or
some which stand with few leaves such as
palm. The grasses, shrubs and trees, which
grow on their own without interference or
help from human beings are called natural
vegetation. Do you wonder how these differ
from each other. Different types of natural
vegetation are dependent on different
climatic conditions, among which the
amount of rainfall is very important.
Due to varied climatic conditions, India
has a wide range of natural vegetation.
Vegetation of India can be divided into five
types – Tropical evergreen forest, Tropical
deciduous forest, Thorny bushes,
Mountain vegetation and Mangrove
forests.

TROPICAL RAIN FOREST

Tropical Rain Forests occur in the areas
which receive heavy rainfall. They are so
dense that sunlight doesn’t reach the ground.
Many species of trees are found in these forests,
which shed their leaves at different times of the year. As a result, they always appear green and are
called evergreen forest look at the Figure 8.1.
Important trees found in these forests are
mahogany, ebony and rosewood. Andaman and
Nicobar Islands, parts of North-Eastern states and
a narrow strip of the Western slope of the Western
Ghats are home of these forests.





TROPICAL DECIDUOUS FORESTS
In a large part of our country we have this type of
forest. These forests are also called monsoon forests.
They are less dense. They shed their leaves at a
particular time of the year. Important trees of these
forests are sal, teak, peepal, neem and shisham. They
are found in Madhya Pradesh, Uttar Pradesh, Bihar,
Jharkhand, Chhattisgarh, Orissa, and in parts of
Maharashtra.

THORNY BUSHES