Clouds Formation and Types of Clouds


This article will clearly explain about Clouds and Classification of clouds.


  • Clouds/clouds are defined as aggregates of several tiny water droplets, ice particles or a mixture of both in the air generally much above the ground surface.
  • Not all clouds produce precipitation, but precipitation will not occur without the formation of a cloud first.
  • Clouds are important factors in the heat energy budget.
  • They absorb some of the incoming solar energy, reflect some of that energy back to space and scatter or diffuse other wavelengths of energy to and away from Earth.
  • Clouds form when air happens to cool, to dew point and vapour condenses in Water droplet and or ice crystals.
  • Two conditions are necessary for cloud formation.They are
  1. Air must be Saturated. (When air of given temperature holds all of the Water Vapour that it possibly can it is said to be in a state of saturation).
  2. There must be a substantial quantity of small particles called Condensation nuclei, around which liquid droplets/ ice crystals are formed when vapour condenses.
  • Cloud indicates the state of Atmosphere and whisper hints about the future weather.


  • The general classification of clouds was proposed by Luke Howard in 1803.
  • Howard’s Classification was a descriptive one and based on the shape of height.Types of clouds



Howard recognised three standard shapes of clouds and used three Latin words for the same.

(1) Cirrus Clouds – Like a lock of curly hair.

  • Cirrus clouds form at very high altitudes, normally 6000-10,000 m, and are made up of ice crystals.

(2) Stratus Clouds – Like a sheet/layer/ceiling of a room.

  • Stratus clouds appear at lower altitudes from the surface up to almost 6000 m.
  • The basic characteristic of stratus clouds is their horizontal appearance, in layers of fairly uniform thickness.

(3) Cumulus Clouds – Like a heap/pile.

  • Cumulus clouds develop vertically rather than forming the more horizontal structures of the cirrus and stratus types.
  • Cumulus clouds provide visible evidence of an unstable atmosphere.
  • He also used the word Nimbus to denote a rain bearing cloud.



There are three subtypes.

1) High clouds(Cirro): Clouds formed at an elevation above 20000 feet(7000 meters).

2) Low Clouds(Strato): Clouds formed at an elevation below 2000 meters (7000 feet).

3) Middle Clouds(Alto): The ones which are formed at elevations between 2000 – 7000 meters. I.e between 7000-2000 feet.


  • Such clouds grow from low bases to a height of as much as 15 km (above 50,000 ft).
  • Such clouds usually have limited horizontal spread (As they are related to localised heating (or) convection).


  • High clouds are mainly cirrus in shape.
  • Low clouds are mainly stratus in shape.
  • Clouds which are vertically developed are mainly cumulus in shape.
  • Howard used the word Alto as the prefix to denote a middle-level cloud.
  • High clouds are composed largely of Ice crystals.
  • Supercooled droplets refer to the microscopic droplets of water at the temperature below 0 degrees C.
  • Middle-level clouds are hugely formed of water droplets which frequently exists in a supercooled State at the temperature well below freezing.
  • Howard also made composite names using the above-mentioned Latin words such as Cumulonimbus Nimbus and cirrostratus.

Plains and Types of Plains

Plains and Types of Plains

This article will clearly explains about Plains and Different types of plains


  • Plain is extensive, relatively level area of land. It exhibits gentle slopes and small local relief.
  • It occupies slightly more than one-third of the land surface. Plains are found on all continents except Antarctica. Some are tree-covered and others are grassy.
  • They have different names in different climates and countries. E.g. steppes, prairies, pampas, veld etc.
  • The cause of the formation of plains included the erosive action of water, glaciation, the draining of a lake, deposition of sediments and the upliftment of a Continental shelf.

Types of Plains

On the basis of their mode of formation, the plains can be of various types.

  1. Structural Plains
  2. Erosional Plains
  3. Depositional Plains

Structural Plains

They are structurally depressed areas, which are largely formed by horizontally bedded rocks relatively undisturbed by crustal movements. E.g. Great plains of the USA, Central lowlands of Australia.

Erosional Plains

They are formed by the action of various Erosional events that work to bring an elevated, region near to the sea level.

  1. Riverine Erosion Plains
  2. Glaciated Plains
  3. Wind Eroded Plains

Riverine Erosion Plains

Riverine Erosion Plains will form peneplains, which are characterised by residual hills known as Monadnocks.

Glaciated Plains

Glaciated Plains forms ice-scoured plain, e.g. ice scoured plains of North-Western Europe and North America.

The Wind Eroded Plains

In arid and semi-arid regions, wind deflation will blow desert materials, lowering the level of land and forming extensive plains, e.g. the Reg of Africa.

Depositional Plains

The plains formed by the filling up of sediments carried by agents of Erosion like wind, rivers, glaciers and underground water into depressions are called Depositional plains.

  1. Riverine Alluvial plains
  2. Glacial Plains
  3. Loess Plains
  4. Lacustrine Plains

Riverine Alluvial Plains

These plains are formed by the deposition of sediments brought down by rivers. It includes Piedmont Alluvial plains, floodplains and delta plains.

Glacial Plains

Glacial Plains are formed by the deposition of unsorted sands and travels brought down by glaciers. Glacial Plains are divided into three types on the basis of composition and structure. Till plains, Morainic plains and Outwash plains.

Loess Plains

Loess Plains are formed due to the deposition of sand and clay brought by the winds. These plains lack in layers but are highly porous. The soil of these plains is very fertile e.g. the Great plain of Northern China.

Lacustrine Plains

Lacustrine Plains are the plains formed by lakes filled by the sediments brought down by the rivers. The valley of Kashmir is an example of this type.

The difference between Structural, Erosional and Depositional Plains

Structural Plains

Structural Plains formed due to the uplift of a part of the sea floor e.g. the Great plain of USA.

Erosional Plains

Erosional Plain formed when the elevated tract of land is worn down by the process of Erosion.

E.g. plain of North Canada.

Depositional Plains

Depositional Plain formed by filling up of sediments into depressions along the foothills, lakes and seas e.g. Info Ganga plain.



Plateaus and Types of Plateaus

Plateaus and Its Types

This article clearly explains about the Plateaus, Types of Plateaus and Famous Plateaus of the world.


The term plateau is applied to any fairly flat high land region a tableland or elevated tract of comparatively flat or level land, the surface of which may be uniformly levelled or have broad Summit heights of fairly uniform elevation.

Plateaus are extensive upland areas characterised by at least one side of very steep slope standing well above the neighbouring surface.

Types of Plateaus

Different types of plateaus are

  1. Intermontane Plateaus
  2. Piedmont Plateaus
  3. DomeShaped Plateaus
  4. Continental Plateaus
  5. Volcanic Plateaus

Intermontane Plateaus

  • These plateaus are surrounded by hills and mountains from all sides.
  • The Tibetan plateau, with a height of about 5000 m, is the most striking example of this type. Other examples are Bolivian plateau, Peruvian plateau, Colombian plateau and Mexican Plateau.

Piedmont Plateaus

  • Plateau formed at the foothill of extensive mountains is called Piedmont plateau.
  • Piedmont plateau is surrounded by a mountain range on one side and by plain or ocean on the other side. E.g. Eastern margins of the Appalachians mountains (USA) and Patagonian plateau of South America.

Dome Shaped Plateaus

These plateaus are formed, when the landmass is uplifted in such a manner that the middle portion is raised and the sides are rounded. e.g. Chotanagpur plateau (India) and Ozark (USA) plateau.

Continental Plateaus

  • These plateaus are formed either due to the  upliftment or extensive spreading of lava on the Earth surface.
  • These are very extensive plateaus and are generally away from mountain areas, but are surrounded by oceanic coasts or plains. e.g. Siberian shield and Canadian shield and Brazilian shield.

Volcanic Plateaus

  • These plateaus are formed due to the accumulation of thick layers of basaltic lavas.
  • Fissure eruption of volcanoes is the main cause for the formation of these plateaus. Deccan lava plateau of India and Colombian plateau of USA are the best example.

Famous Plateaus of the World

Plateau Situation
Tibetan Plateau Between the Himalayas and the Kunlun Mountains
Deccan Plateau Southern India
Arabian Plateau South-West Asia
Plateau of Brazil Central-Eastern South America
Plateau of Columbia North-west North America
Plateau of Bolivia Andes mountains
Great Basin Plateau South of Columbia Plateau, USA
Colorado Plateau South of Great Basin-Plateau, USA

This is the brief information about Plateaus and its Types. If you like this article Share or Like it, or if you want to know more comment below.

Mountains and different types of Mountains

Mountains and Types of Mountains

Mountains are significant relief features of the second order on the Earth’s surface. Generally, the mountains are more than 1000 m high.

The mountains, whose height is less than 1000 m, called hills. Cordillera includes a general highland formed in a different period and by different processes.


  • The word Orogeny comes from two Greek words, viz, oros mean mountain and geny mean creation. It is the primary mechanism, by which mountains are built on the continents. E.g. the Himalayas, Alps, Atlas, Rockies and Andie’s etc.
  • The mountains are formed by upward and downward displacement of the Earth’s crust. This displacement is due to folding, faulting and compressional forces of the Earth’s crust. Thus, mountain building can be represented by orogenic belts.

Orogenic Belts

  • These are the mobile belts arranged in linear or arcuate tracts that have been subjected to severe deformation and mountain building and are typically found near the edges of the continents. These are two significant aspects of its location.
  • The young fold mountain belts found along the Continental margins e.g. Rockies and Andes. Many older mountain belts extend to the ocean and abruptly terminate at the continental margins. E.g. Northern Appalachian and Atlas mountains.

Types of Mountains

On the basis of orogeny, the mountain can be classified as

  1. Fold mountain,
  2. Block Mountain and
  3. Volcanic mountain.

Fold Mountains

  • Fold Mountains formed when a thickly bedded sedimentary layer is subjected t horizontal compressional forces for millions of years. The sediments get bend into up and down -folds. This leads to the formation of anticlines and synclines.
  • These mountains are characterised by a more developed system of anticlines and synclines wherein folds are arranged in a wave-like pattern.

Types of Fold Mountains

Fold Mountains are further classified as

  1. Young Fold Mountains.
  2. Mature Fold Mountains.
  3. Old Fold Mountains.

Young Fold Mountains

The Himalayas, the Alps, the Rockies, Andes, Atlas and the Southern Alps.

Mature Fold Mountains

The Pennines, the Appalachians and the Cape range of Southern Africa were formed during the Carboniferous age.

Old Fold Mountains

The high mountains of Scotland and Norway, the Sayan and Stanovai mountains of Russia and the Aravali and Mahadev mountains of India.

Block Mountains

  • These mountains originate due to tensional force leading to the formation of Rift valley.
  • The Block Mountain or Horst represents the upstanding parts of the ground between two faults or on either side of a Rift valley or a Graben.
  • The Vosges in France, Black Forest Mountains in Germany and Sierra Nevada in Northern America are the typical examples of Block Mountains.

Volcanic Mountains

The continuous deposition of lava over Earth’s surface leads to the formation of a conical peak. It is called volcanic peak. Like mountain Mauna Kea over Hawaii in the Pacific Ocean.

Major Mountain Ranges

Range Location Length(km)
Andes South America 7200
Rockies North America 4800
Great Dividing Range East Australia 3600
Himalaya India, Pakistan, Nepal 2400
Atlas North-west Africa 1930
Western Ghats Western India 1610
Caucasus Europe 1200
Alaska USA 1130
Alps Europe 1050

Standard Time and International Meridian Conference

Standard Time and International Meridian Conference (IMC)

Standard Time and International Meridian Conference (IMC) are one of the important topics in UPSC Examinations. So, I think this article will surely helpful for your Examinations.

Standard Time 

  • Before the middle of 19th century, 100’s of different time system were in use, throughout the world, based on the rising of the sun.
  • Sir, Sanford Fleming led the fight in Canada for Standard time and for an International agreement upon prime meridian. His Struggle lead, United States, Canada to adopt Standard Time in 1883.
  • In 1884 International Meridian Conference (IMC) in Washington DC, to avoid confusion. We follow uniform time throughout the country, such uniform time is based on central meridian of the country or meridian on which most important city is located.
  • Such a Central meridian is called Standard Meridian for India, 82 ½° East. Generally central meridian is taken in such a way by that it is divisible by 7½°.
  • So that the standard time differs from GMT ( Greenwich Mean Time) by multiples of half an hour.
  • Countries which have vast longitude extension do not have a standard single time for the whole country.
  • Generally such country goes for more than 1-time zone each approximately 15° of longitude.
  • China extends across 4 fifteen degrees zone, the entire nation at least officially observe the time of 120° E meridian close to china’s capital.

International Meridian Conference (IMC) 1884.

  • The world was divided into 24 standard time zones each extending over 15° of longitude.
  • The local solar time of the Greenwich was chosen as the standard for the entire system.
  • The prime meridian (PM) became the centre of a time zone that extends 7½ of longitude both to the west and to the east of the Prime Meridian.
  • Similarly, the meridians that are the multiples of 15, both cast and west of the meridian, were set as the central meridians for 23 other time zones, each of which is 15° of longitude in extent.
  • 12 zones to the east of Greenwich meridian were designated to be ahead of the time at Greenwich by 1 hour per zone. Similarly, 12 zones to the west of GreenWich are behind.
  • In International waters, these time zones are shown exactly 7½ to east and 7½° to the west of the central meridians.
  • Over land areas, however, the actual eastern and western boundaries of time zones vary to coincide with appropriate political and economic constraints.

This is the article about Standard time and International Meridian Conference

Forces acting on the moving air near the Earth’s surface

Forces acting on the moving air near the Earth’s surface

There are three forces acting on moving air near the Earth’s Surface. They are

  1. Pressure Gradients Force (PGF)
  2. Coriolis Force.
  3. Forces of Friction.

(1) Pressure gradient force (pgf)

Pressure Gradient Force is the basic activating force for the wind. I.e. it initiates the movement of air.

They are two types

  1. Gentle Pressure Gradient (slow movement of wind).
  2. Steep Pressure Gradient (Faster movement of wind).


Pressure Gradient Force attempts to take the air from high pressure zone to low pressure across the isobar in a perpendicular direction.

(2) Coriolis Force

Because of earth rotation, all moving bodies on the earth appear to get deflect.

To account for that apparent deflection the scientists has proposed a force calledCoriolis law (named after French Mathematician – Gespard coriolis).


There is a law about this force – ” ferrels law of deflection “.

Ferrels Law states “the effect of Coriolis force on a moving body – there is an apparent deflection of moving body to its right in the Northern Hemisphere and to its left in the Southern Hemisphere.”

This Coriolis Force is negligible near the equator and it increases towards the pole.

The reason for this lies in the effect that the earth’s speed decreases as we more from Equator to the poles and the rate of this is decreases is a function of Latitude (rate increases  towards the pole).

(3) Forces of Friction:

Forces of Fraction
Forces of Fraction

Speed decreases, modifies the direction. The Frictional drag of this Earth’s surface acts both to slowdown wind movement and to modify its direction of Flow.

Zone of Convergence of Air

Zone of Convergence of Air is a Zone where there is net in flow of air. A low pressure zone is a zone of convergence of air.

Zone of Divergence of Air

Zone of Divergence of Air is a zone where there is net out flow of air. A high pressure zone is a zone of divergent of air.

Cyclone and Anticyclone

A Cyclone is a wind system with a Low pressure at the centre, An anticyclone is wind system with a high pressure at the centre.

Latitude, Longitude, Parallel and Great Circle

Latitude, Longitude, Parallel and Great Circle


″ Latitude is the Angular distance measure North (N) and South (S) of the equator. We can project the line from the point P from the earth surface to the centre of the Earth. ″

  • The angle between this line and equator plane is the measure of the latitude of point P.
  • Latitude varies from 0° to 90° North or South.


The parallel is a line connecting all points of the same latitude. It is called so because it is parallel to all other lines of Latitude.

0° Parallel – Equator.

90° North  – the North Pole.

90° South  – the South Pole.

Longitude :

Longitude is the angular distance between meridian passing through a given point and prime meridian

  • The Longitude varies from 0° to 180° East or West.
  • Meridian is a line joining places with the same longitude.

Great Circle

Any plane that is passed through the centre of sphere bisects that sphere and creates a great circle where it intersects the surface of the sphere.

  • A great circle is the largest circle that can be drawn into the sphere and it represents the circumference of the sphere.
  • Of all the parallels The Equator alone makes a great circle all other parallel makes the small circle.
  • Each meridian makes Semi Great Circle.
  • Arc of the great circle joining any part on the equatorial surface is always the shortest route between points.

Circle of Illumination 

Sun Illuminates one-half of the earth at any given moment. The edge of the sunlight hemisphere, the circle of illumination, is a great circle, that divides the Earth into the light half and dark half.

Important Parallels 

Both 23 1/2 ° N and  23 1/2 ° S will receive 90° sunlight and these two tropics represent the farthest limit of the vertical base of the sun

” Tropi” in latin – Tropics, Meaning “Turn”.

This is about the Great Circle if you like this article share or comment below.

Mountains, Plateaus, Plains and its Different Types

Mountains, Plateaus, Plains and its Different Types

In general, geomorphic processes that originate within Earth, called endogenic processes result in an increase in surface relief, while the exogenic processes, those that originate at Earth’s surface, tend to decrease relief.  Igneous and tectonic processes constitute the endogenic geomorphic processes.

Exogenic processes consist of various means of rock breakdown, collectively known as weathering, and the removal movement, and relocation of those weathered rock products in the continuum of processes known as erosion, transportation and deposition. These processes decide the landforms on earth.


Compressional Tectonic Forces are divided into two types. They are

  1. Folding and
  2. Faulting


Folding, which is a bending or wrinkling of rock layers, occurs when compressional forces are applied to rocks that are ductile (bendable), as opposed to brittle.

Compressional-Tectonic Forces-(Folding)

  • Rocks that lie deep within the crust and that are therefore under high pressure are generally ductile and particularly susceptible to behaving plastically that is, deforming without breaking.
  • As a result rocks deep within the crust typically fold rather than break in response to compressional forces.
  • As elements of rock structure, unfolds are called anticlines, and downfolds are called synclines.
  • The rock layers that form the flanks of anticlinal crests and synclinal troughs are the fold limbs.


  • Faulting is the slippage or displacement of rocks along a fracture surface, and the fracture surface along which movement has occurred is a fault.
  • When compressional forces cause faulting either one mass of rock is pushed up along a steep-angled fault relative to the other or one mass of rock slides along a shallow, low-angle fault over the other.
  • The steep, high-angle fault resulting from compressional forces is termed a reverse fault.
  • Where compression pushes rocks along a low-angle fault so that they override rocks on the other side of the fault, the fracture surface is called a thrust fault, and the shallow displacement is an overthrust.


  • In both, reverse and thrust faults, one block of crustal rocks is wedged up relative to the other.
  • Reverse or thrust faulting can also result from compressional forces that are applied rapidly and in some cases to rocks that have already responded to the force by folding.


  • In the latter case, the upper part of a fold breaks, sliding over the lower rock layers along a thrust fault forming an overthrust.
  • Together recumbent folds and overthrusts are important to rock structures that have formed in complex mountain ranges such as the Andes, Alps, and the Himalayas.


Types of Mountains

Based on their mode of formation, four main types of mountains can be distinguished.

They are

  1. Fold Mountains
  2. Block Mountains
  3. Volcanic Mountains
  4. Residual Mountains

1.Fold Mountains:

  • They are caused by large-scale earth movements when stresses are set up in the earth’s crust.
  • When such stresses are initiated, the rocks are subjected to compressive forces produce wrinkling or folding along the lines of weakness.


  • The unfolded waves are called anticlines and the troughs or downfolds are synclines.
  • Due to the complexity of the compression forces, the folds developed much more complicated forms.
  • When the crest of a fold is pushed too far, and over fold is formed.  If it is pushed still further, it becomes a recumbent fold.
  • In extreme cases, fractures may occur in the crust, so that the upper part recumbent fold slides forward over the lower part of a thrust plane, forming an overthrust fold.  The over-riding portion of the thrust fold is termed a nappy.

2.Block Mountains:

  • When the earth’s crust bends folding occurs, but when it cracks, faulting takes place.
  • Faulting may be caused by tension or compression, forces which lengthen or shorten the COMPRESSION earth’s crust, causing a section of it to subside or to rise above the RIFT VALLE surrounding level.
  • Examples are the Huns Ruck Mountains, the Vosges and Black forest of the Rhineland.

3.Volcanic mountains:

  • These are in fact, volcanoes which are built up from material ejected from fissures in the earth’s crust.
  • The materials include molten lava, volcanic bombs, cinders, ashes, dust and liquid mud.
  • They fall around the vent in successive layers, building up a characteristic volcanic cone.
  • Volcanic mountains are often called mountains of accumulation.

Residual mountains:

These are mountains evolved by denudation. Where the general level of the land has been lowered by the agents of denudation some very resistant areas may remain and these form residual mountains.


Plateaux are elevated uplands with extensive level surfaces and usually descend steeply to the surrounding lowland.  They are sometimes referred to as tablelands.

Types of Plateaus

There are three types of Plateaus. They are

  1. Tectonics Plateaus
  2. Volcanic Plateaus
  3. Dissected Plateaus

Tectonics Plateaux:

  • These are formed by earth movements which cause uplift, and are normally of a considerable size, and fairly uniform altitude.
  • They include continental blocks like the Deccan plateau in India. When plateaux are enclosed by fold mountains, they are known as intermont plateaux.
  • Examples are the Tibetan plateau between the Himalayas and the Kunlun,  and the Bolivian Plateau between two ranges of the Andes.

Volcanic Plateaux

  • Molten lava may issue from the earth’s crust and spread over its surface to form successive sheets of basaltic lava.  These soldify to form a lava plateau.
  • Some of the better known volcanic plateaux are the Antrim plateau of Northern Ireland and the north-western part of the Deccan plateau.
  • The most remarkable plateau built by lava is the Colombia-snake plateau which covers an area almost twice as big as Malaysia.

Dissected Plateaux:

  • Through the continual process of weathering and erosion by running water, ice and winds, high and extensive plateaux are gradually worn down,  and their surfaces made irregular.
  • In the humid highlands, stream action and sometimes glaciation cut deep, narrow valleys in the plateaux, which are then described as dissected plateaux.
  • An example is the Scottish Highlands.  In drier countries, vertical corrosion by rivers and abrasion by winds will dissect the plateau into steep-sided tabular masses termed as mesas and buttes, intersected by deep canyons.
  • This is a common feature of arid and semi-arid areas,  e.g;  in the south-western U.S.A.


A plain is an area of lowland, either level or undulating.

Types of plains

There are three types of plains. They are

  1. Structural Plains
  2. Depositional Plains
  3. Erosion Plains.

Structural plains

  • These are the structurally depressed areas of the world that make up some of the most extensive natural lowlands on the earth’s surface.
  • They are formed by horizontally bedded rocks, relatively undisturbed by the crustal movements of the earth.

Depositional plains:

  • These are plains formed by the deposition of materials brought by various agents of transportation.
  • They are comparatively level but rise gently towards adjacent highlands.  Some of the largest depositional plains are due to deposition by large rivers.
  • They are called alluvial plains, flood plains and deltaic plains.  They form the most productive agricultural plains of the world, intensively tilled and very densely populated.
  • The Nile delta of Egypt is noted for rice and cotton cultivation, the Ganges delta for rice and jute growing, while the plain of North China, where the Hwang Ho has spread out a thick mental of alluvium, supports a wide range of crops.
  • Glaciers and ice-sheets may deposit a widespread mantle of unsupported fluvial glacial sands and gravels in the out plain or may drop boulder clay, a mixture of various sizes of boulders and clay,  to form a till plain or drift plain.
  • Outwash plains are usually barren lands, e.g.  Some parts of Holland and northern Germany, but boulder clay may be very valuable farming land e.g. the Mid-West of the U.S.A.  and East Anglia in England.
  • In coastal regions, waves and winds often drive beach materials, mud, sand or shingle,  landwards and deposit them on the coastal plain to form marine swamps,  mud-flats,  tidal and estuarine lowlands.
  • Winds may blow Aeolian deposits very fine particles known as loess-from interior deserts or barren surfaces and deposit them upon hills, valleys or plains forming a loess plateau as in north-west China,  or loess plains,  as in the Pampas of Argentina.
  • The loess helps to level an undulating plain by filling up grooves and depressions.

Erosion plains:

  • These plains are carved by the agents of erosions. Such plains of denudation are described as pen plains.
  • Mechanical weathering in arid and semi-arid areas wears back the mountains slope to leave a gently sloping pediments or Pedi plains.