Category: Geography Notes PPT

In the lower atmosphere of the earth, particularly in the troposphere zone, we observe the different atmospheric phenomena. The wind is one such element in the earth that controls various changes in the weather phenomenon. To understand the Gale meaning, first, we have to understand that it is also a form of wind. But in Gale, the wind is much stronger than a normal breeze. The wind velocity in the gale is about 50-102 Kilometers and number 7 to number 10 on the Beaufort Scale. A warning about gale is issued by the Weather Service when wind velocity is 34 – 47 Knots or 63 – 87 Kilometers per hour. Gale, meaning in English, is nothing but a strong wind force. We can also call it Fresh Gale.

Gale Company is basically a group that is very much active in doing research. The company used to publish academic, school library, and business magazine and newspaper databases. Gale eBooks’ also cover a wide range of geography topics, including maps, continents, about the people and environment.

To know about the life of David Gale, a popular movie character, we have to go through the movie. David Gale is a professor in Texas, US. He is about to die, and his lawyer explained his life story and secrets. David gale is a famous personality for keeping secrets. Gale is the head of the department at the University of Austin.

Gale and other Wind Force

A famous scientist gives an interesting way to know the relationship between wind direction and horizontal pressure. This famous Dutch scientist in 1857 gave the law Buys Ballot’s law. After doing certain research about the wind, he stated a formula empirically. According to him, a person will experience high wind pressure on the right side and low pressure on the left side when he will stand in the Northern hemisphere, and he will experience the opposite when he is in the Southern hemisphere.

As per this relation, the angle between the wind and the pressure gradient is a right angle. But later, it was revealed that this phenomenon is true in the free atmosphere but not near the ground surface. The angel is always less than 90 near the ground. This is mainly due to the frictional force between the air and the surface and tends to move the air towards the lower atmospheric pressure areas. But this law is not applicable in the equator region because of the weakness of the Coriolis effect, which is mainly formed due to the rotation of the earth.

The name Gale originates from the ancient Norse word Gallin which means mad. But weather forecasts sometimes use this term to signify wind force which is not extreme like hurricanes but a very strong wind force. Gale is also like a bad Tornado because its damage symptom is broad here as it has the ability to uproot shallow-rooted trees. Gale is mainly associated with coastal regions because here, the wind speed is a bit more. The minimum wind speed here is 50 kilometers per hour, and it can extend up to 102 km, so it can be dangerous and have the ability to destroy.

Hail is a kind of solid precipitation, different from ice pellets. It includes balls or irregular lumps of ice, each of which is known as a hailstone. Ice pellets generally fall in cold weather whereas the growth of hail is immensely constrained at cold surface temperature. In contrast to ice pellets, hailstone usually measures between 5 mm (0.2 in) and 15 cm (6 in) in diameter. Hailstone is most commonly found in mid-latitudes and usually lasts around 15 minutes. They generally occur in mid – to -late afternoon. 

Hail is extremely destructive to crops and buildings if large enough, or it may be even dangerous to animals exposed to it.

Hailstorm Definition  

Any thunderstorm through which hail is produced and reaches the ground is known as a hailstorm. Hail has a diameter of 5 mm (0.20 in) or more and can grow to 15 cm (6 in) and weighs more than 0.5 kilograms.

In contrast to ice pellets, a hailstone is stratified and can be irregular and clustered together. Hail consists of transparent ice and alternating layers of transparent and translucent ice at least 1 mm ( 0.039 in) thick, which are laid down upon the hailstone as it travels through the clouds, held off above by air with strong upward motion until its weight exceeds the updraft and falls to the ground. 

The diameter of hail is generally varied, in the United States, the damaged hail, on average, is observed between 2.5 cm (1 in) and golf ball-sized  ( 1.75 in). Stones larger than (0.80 in) are considered to be large enough to cause damage.

Hailstone Formation

Hailstone formation or hail formation occurs when the rain droplets are carried upward through thunderstorm updraft into immensely cold areas and freezes. Hailstones then further grow by hitting liquid water droplets that freeze into the surface of the hailstone. If the water freezes speedily when hitting the hailstone, cloudy ice will form as the air bubbles will be confined in the newly formed ice. However, if the water evaporates slowly, the air droplets will escape and the newly formed ice will be clear. The hails fall when thunderstorm updraft can no longer support thunderstorms weight, which can come about if the stone becomes large enough or the updraft weakens.

Hailstone Meteorology Size

The hailstone size can be best described by measuring the diameter using a ruler. In the absence of a ruler, the hailstone size can be best estimated by comparing its size to that of known objects, known as coins. Comparing the hailstone size using the objects such as eggs, peas, marbles is imprecise due to the varied dimensions. The UK organization, TORRO also measures for both hailstone and hailstorms.

When observing the hail at an airport, METAR code is used within the surface observation which is related to the size of the hailstone. The GR within the metric code is used to represent the larger hail, of a diameter of the latest 0.25 inches (6.4 mm).

The terminal velocity of hail or the speed at which hailstone is falling when striking the ground changes. It is estimated that a hailstone of 1 cm (0.39 inches) in diameter falls at a rate of 9 meters per second (20 mph) while the stone size of 8 cm (3.1 inches) in diameter falls at a rate of 48 meters per e camph. The speed of hailstone cannot be determined accurately as they are not in spheres. 

Did You Know?

• Hailstone can fall at a speed between 9 mph (14 km/hr) and 110 mph (17 km/hr).

• The larger hailstones are faster to fall.

• The hailstorm most commonly occurs in one of the areas of the United States known as the hail alley.

• Hailstorms are formed when thunderstorms carry rain droplets up into the extremely cold areas of the Earth’s atmosphere.

• Approximately 200 to 600 nomads seem to have died of injuries. The haistone of thel size of a cricket ball occurred around the 9th century in Roopkund, Uttarakhand, and India.

Iceberg Meaning: (noun) a Massive Block of Ice That Floats in the Sea.

What is an Iceberg?

Iceberg Definition- Icebergs are a large moving mass of ice chunks that break off from the glaciers. This is known as calving. Icebergs float in the ocean but are composed of frozen freshwater rather than saltwater. Refer to the below image to understand how an iceberg underwater looks like.

Types of Iceberg

To be classified as an iceberg, the ice must be at least 16 feet above sea level, have a thickness of 98-164 feet, and cover an area of at least 5,382 square feet.

Smaller ice chunks are known as “bergy bits” and “growlers.” 

Bergy bits and growlers can come from glaciers or shelf ice, or they can be the result of a large iceberg breaking up. A bergy bit is a medium to large ice fragment. Its height is typically greater than three feet but less than sixteen feet above sea level, and its area is typically between 1,076-3,229 square feet. 

Growlers are smaller ice chunks about the size of a truck or a grand piano. They are about 215 square feet in size and extend less than three feet above the sea surface.

Icebergs are also classified according to their shape, which is typically tabular or non-tabular. Tabular icebergs are distinguished by steep sides and a flat top. non-tabular icebergs have a variety of shapes, including domes and spires.

Are Icebergs Dangerous?

Iceberg underwater is dangerous to ships. The sharp, hidden ice can easily tear a hole in a ship’s bottom. Because of the large number of icebergs that have found their way there, a particularly dangerous section of the North Atlantic has come to be known as Iceberg Alley. Iceberg Alley is located in Canada, 250 miles east and southeast of Newfoundland.

The Titanic, a large British ocean liner on its way to New York in 1912, collided with an iceberg and sank in Iceberg Alley. More than 1500 people perished in the flood. The International Ice Patrol was formed soon after the Titanic sank to track icebergs and warn ships. That patrol is still going on today.

What are Active Safety Measures?

The National Ice Center of the United States monitors icebergs all over the world (NIC). NIC analyses and forecasts ice conditions in the Arctic, Antarctic, Great Lakes, and the Chesapeake Bay. The National Ice Center (NIC) is the only organisation that names and tracks all Antarctic icebergs.

Iceberg patrols now use global positioning system (GPS) technology to help locate icebergs and prevent future disasters like the Titanic. The National Ice Center lost track of an iceberg the size of Rhode Island in 1999. It was discovered drifting toward the Drake Passage, a vital shipping route south of Argentina. Dr David Long of NASA’s SeaWinds science team tracked the iceberg using satellite data, the first time satellite technology was used for that purpose. Since then, the SeaWinds team has tracked the world’s ice using satellites.

Additional Information

The disease pattern in the community or population is described using the analogy of an iceberg. The study of the “iceberg phenomenon of a disease” describes how a disease progresses (pathogenesis and spread) from its subclinical stages to its apparent disease state. The tip of the iceberg represents what clinicians see, while the submerged portion is what epidemiologists explore and make visible. The largely hidden part of the iceberg is what makes up the majority of unrecognised disease in the population and determines the fate of any disease control programme.

• Have you heard of Iceberg Principle? Ernest Hemingway invented the Iceberg principle, also known as the theory of omission, as a writing strategy. Hemingway had to base his newspaper reporting as a young writer on current affairs with no meaning or explanation. He maintained this minimalistic approach as a short story writer, concentrating on surface elements rather than directly addressing overarching concepts. The deeper sense of a plot, according to Hemingway, should not be obvious on the surface but should shine through indirectly. 

The ionosphere and magnetosphere are considered as the regions of the atmosphere of the earth which contains a large number of electrically charged particles. These electrically charged particles are also known as ions and electrons. The radio waves are propagated through these particles as they are large enough. Extraterrestrial radiation that usually comes from the sun creates these charged particles. These are mainly made on the molecules of air and neutral atoms. The Approximate height of the ionosphere is around 50 km that is 30 miles above the surface of the earth.

               

         

Layers of Ionosphere

Traditionally, there are several different layers under the ionosphere. When the discovery of the ionosphere was done, it was found that there were many layers present. The layers were named D, E and F under the ionosphere.

Ionospheric Regions

D, E and F layers are best for structuring out the ionosphere. The level of ionization in the ionosphere changes with altitude. There are peaks in each level of the ionosphere which are called different regions or layers. Along with these regions, there is a C region also under the ionosphere. But the fact is that the ionization level is a bit low as compared to other regions. C region does not affect radio communications and radio signals. There are dissimilar regions under the ionosphere and they have different features and also affect radio signals differently. The ways these regions are created are also different.

D Region

When the surface of the earth is left behind after the skywave and starts moving upwards then the initial region that reaches the ionosphere is known as the D region. D region is present between 60 km to 90 km at altitudes. Several factors are dependent on when there is a loss of signal. The factors are the level of ionisation, frequency of the signal and frequency of the signal.

E Region

E region is considered as a step above the D region. The altitudes of the D region is between 100 km to 250 km. Wherever the existence of the E Region takes place, the air density will be seen less as compared to the D region. The reason why it happens is that the electrons are released out due to vibration and signals and then some of the collisions only occur. Hence the E region is somewhat not similar to other regions.

F Region

Among all the regions in the ionosphere, the F region is considered the most essential region in terms of radio communication. In the presence of the sun, the radiations are being released from the sun and most probably they are divided into two regions. Firstly, the F1 region is considered as the lower one and secondly, the F2 region is a higher one. If the infection point is taken into view then the F1 region will be considered. 

Some Facts about Ionosphere 

• The ionosphere overlaps the top of the atmosphere and the sun cooks gases there until or unless they lose an electron or two that creates a sea of electrically charged particles. Thus, this Ionosphere becomes the shelter to all the charged particles in the Earth’s atmosphere.

• The ionosphere stretches 50 to 400 miles above the earth’s surface and this is just right at the edge of space. Along with this the Ionosphere also forms the boundary between the Earth’s lower atmosphere where we can live and breathe in a proper way. So, the Ionosphere is the part where the earth’s atmosphere meets space.

• The ionosphere is the home to many of our satellites including the international space station. This means these satellites can be affected by the constantly changing conditions in the Ionosphere. This also includes the sudden swells of the charged particles which can increase the drag on satellites and shorten the orbital lifetimes.

• The ionosphere has a great role in everyday communications and navigation systems. For this reason, we are able to get the sound from Radio and GPS signals. In both cases, the Ionosphere’s composition and density can disrupt these signals.

• The ionosphere can be influenced by the weather. Different weathers like thunderstorm systems, hurricanes can create pressure waves that ripple up into the Ionosphere. NASA has done research on this matter and within the past 15 years, NASA satellites revealed the connections between the weather condition changes in Earth’s Ionosphere.

• Besides these, the Ionosphere can be influenced by the space weather and this glows constantly also.

In this topic, we’ll study one of the world’s most famous river basins, the Ganga Brahmaputra basin which is driven by the two important rivers, i.e., the Ganga and the Brahmaputra which flows in the Indian subcontinent. We’ll cover the life in Ganga Brahmaputra Basin including the location, topography, agriculture, tourism, transport, etc.

Ganga Brahmaputra River Basin

The basin formed by the tributaries of the Ganga and the Brahmaputra rivers is called the Ganga Brahmaputra Basin. The fertile plains, the Himalayas, and the delta of Sunderbans are the main features of this basin. This area is also replenished by the heavy showers of the monsoon season, bringing rainfall from June to September every year. This basin is having hot summers and cold winters.

Ganga Brahmaputra Basin Location

The Ganga Brahmaputra basin lies in the Indian subcontinent. It lies in the subtropical regions situated between 10°N to 30°S latitudes.

The Ganga Brahmaputra Basin covers a large area in the continent of Asia. It is not limited to any one country or state. It is spread across five countries. The countries that the Ganga Brahmaputra Basin covers are as follows:

• India

• Nepal

• China

• Bhutan

• Bangladesh

In India, it is spread across 10 states and 1 Union Territory. The names of the States or Union Territories that the Ganga Brahmaputra Basin covers are as follows:

• Uttar Pradesh

• Uttarakhand

• Madhya Pradesh

• Rajasthan

• Himachal Pradesh

• Haryana

• Chattisgarh

• Jharkhand

• Bihar

• West Bengal

• Delhi

Tributaries of Ganga Brahmaputra Basin

The Ganga and the Brahmaputra rivers have several left bank and right bank tributaries. Ghaghra, Gandhak, Son, Chambal, and Kosi rivers are the tributaries of the Ganga river which join the basin whereas Teesta and Meghna are the tributaries of the Brahmaputra river which joins the basin. Check out the map given above to get a clear idea of the tributaries.

Topography of the Ganga Brahmaputra Basin

The topography of the basin is not the same everywhere. It is varied in different places. The plains of the Ganga and the Brahmaputra basin are one of their kind and they are world-famous. However, the basin not only includes the plains but also the mountain regions which are having steep slopes such as the mountain ranges of Uttarakhand, Sikkim, regions of Nepal, etc.

Demography of the Ganga Brahmaputra Basin

The demography of the region depends upon various factors like the topography of the region, the climate, rainfall, infrastructural facilities, livelihood opportunities, etc.

• The plains of the basin are densely populated such as Uttar Pradesh, Bihar, Madhya Pradesh, etc.

• The mountain regions of the basin are having less population such as Uttarakhand, Himachal Pradesh, etc.

Wildlife in Ganga Brahmaputra Basin

There is a wide range of wildlife found in the Ganga-Brahmaputra basin. The important Ganga Brahmaputra Basin animals are as under.

• The common wildlife includes elephants, tigers, monkeys, and deers.

• One Horned Rhinoceros of India is also part of this basin, having the maximum population in Kaziranga National Park, Assam which comes under the Brahmaputra Plains.

• Bengal Tiger, crocodiles, and alligators are found in the delta region.

• Rohu, Catla, and Bisla are the most popular fishes found here.

• A unique variety of dolphins is found in the freshwater of the Ganga and the Brahmaputra rivers, namely the Susu Dolphin which is also called a Blind dolphin. The presence of this dolphin indicates the good health of the rivers.

Vegetation and Agriculture of the Ganga Brahmaputra Basin

The basin is a mixture of different kinds of landforms which leads to different vegetation and agricultural activities.

• In the plain areas, tropical deciduous trees are there. The bamboo groves are common in the plains of the Brahmaputra.

• Mangrove forests are found in the delta regions of the basin.

• Coniferous trees are found in hilly areas of Uttarakhand, Arunachal Pradesh, and Sikkim.

• Paddy is the main crop here because of the easy and sufficient availability of water.

• Wheat, maize, millets, gram are the other crops.

• Cash crops like sugarcane and jute also grown here.

• Banana and tea plantations, silk cultivation are also part of agricultural activities here.

Transport and Tourism

All forms of transportation are well developed in the Ganga Brahmaputra Basin.

• Roadways are railways that are the major source of transportation developed everywhere in this basin. The two longest National highways ie. NH 44 and NH 27 passes through this basin.

• The railway station of Gorakhpur Junction, having the World’s longest platform is also situated here. 

• Among the National Waterways, NW 1 and NW 2 are also developed here.

• Various National and International airports are also present and we’ll develop here.

A lot of tourist places are also found here in the basin which is one of the major sources of livelihood.

• One of the seven wonders of the modern world i.e The Taj Mahal is situated here.

• Various National Parks or Tiger reserves or Ramsar Sites are part of the basin. For example Panna National Park, Kaziranga National Park, Sunderbans, etc.

• Various temples or stupas are also present here such as the Gaya Buddhist site, temples of Varanasi, etc.

Did You Know?

The Ganga is a sacred river in the country. The water of the Ganga got polluted so much over the years because of heavy industries and various rituals. Thus, the Government of India launched Namami Ganga Programme for the conservation and cleanliness of the water of the Ganga.

Here we have covered life in the Ganga Brahmaputra basin. Under this, we learned about Ganga Brahmaputra Basin location, tributaries of and wildlife in Ganga Brahmaputra basin or states in which Ganga Brahmaputra basin lies, etc. These notes will help the students of Class 7 and 9. Not only this, but these will also help in enriching your General Knowledge.

Map scales are useful to understand the sizes of objects and distances between objects (their relative sizes) in comparison to the actual sizes of objects and distances between them. This means that on a map it is not possible to denote the actual distances between objects or their sizes since then the map would need to be as big as the objects being measured. This would defeat the purpose of having a map in the first place. 

This is what it means when it is said that maps are drawn to scale. Scales are always mentioned on the maps so that whoever looks at them can get an idea of how to navigate through them. The scale represents how much the area on the map corresponds to the actual area on the ground that it shows. For example, if a map is drawn to a scale of one inch to one kilometre, it would mean that one inch on the map is equivalent to one kilometre on the ground. 

Classification of Maps

To understand what a map scale is, let us go through a few classifications of maps and map scales first. As per the common classification of maps, there are about five types of maps – thematic maps, general maps, navigation charts, topographic maps, series maps, cadastral, and plans. The types of map scale representations are discussed below. The basic type of representation of actual distance on maps is done by bar scales and lexical scales. In the bar scales used in maps, the distance ratio is expressed visually whereas, in lexical scales, the ratio is stated in words. 

There are 3 ways of representing the scale of a map, namely, representative fraction, verbal, and graphic. Out of these three, the representative fraction is the most commonly used scale. For example, the topographic maps help to understand the contour and general landforms of an area and most have the scale stated in representative fraction. In topographic maps, various colours are used to represent the contour of landforms, water bodies, settlements. 

Map Projections

Map projections are used to draw the parallels and meridians of the Earth systematically, on a flat surface. Various map projections are used to represent the landforms on maps. There are certain map projections that have equal-area properties. Also, projections that have the feature of conformal delineations are devised to represent the landforms on maps. 

In certain cases, the outlined shape of very small regions is nearly represented in the same way on the map as it is on the ground. It is not possible to completely avoid distortions of shapes of land areas on large-scale maps. The only way to reduce the distortions is to devise the most suitable for the purpose of the particular map. 

In general, the Mercator projection is devised on the navigational charts. The charts for the polar regions and the great circle charts do not devise the ordinary Mercator projections. The Great Circle charts that represent large map areas are generally depicted on quite small scales devising gnomonic projection. For example, the navigational chart for the Pacific Ocean. The navigators use these charts to lay a track between two ports and calculate the shortest distance between the ports.         

Symbolization

Symbols are the graphical representations of landforms, water bodies, winds, ocean currents, settlements, transport, and communication systems for maps. It may be said that symbols make a graphical language for maps and charts. The symbols were originally ordinary pictograms, which have now developed into conventional signs and symbols for the representation and interpretation of maps.

Standardization of symbols has been brought about by the joint efforts of the UN, NATO, International Map of the World agreements, and the international technical societies. It helped to reduce the confusion that used to arise in the interpretation of maps. The symbols can be classified as hypsographic and planimetric. These symbols can also be grouped based on conventional colours. 

For example, the blue colour is used to represent water bodies, black colour is used to represent occupation, cultures, and names of population, green colour is used to depict vegetation, brown colour is used to depict relief features, and red colour is used to depict types of roads and other special information. This is the standard use of colours, but there may be variations for geologic and soil maps. Planimetric features are used to represent the slopes, heights, and shapes of the land, on a map.

Nomenclature

To enhance the utility of maps, all the possible features and places are identified and labelled on a map. However, for the small-scale maps, only the important features and places are labelled, to enhance legibility. The nomenclature of maps has various parts. The geographic names are among the most troublesome parts of map nomenclature. The large-scale maps permit the naming of the minor features like streams, hilltops, ridges, etc. While making a topographic map, extensive research and documentation are carried out. 

Also, the local records are referred to for identifying and labelling all the parts of the area under concern. When a topographical map is published and distributed, it is used as an official document that eliminates confusion regarding the nomenclature of the local areas. The basic types of lettering that are used in the maps are Roman style, Italic, and Gothic style. 

What is the Significance of the Map Scale?

Map scales give people an accurate idea about how the distances mentioned are plotted on the map. This is useful in understanding how to go from one place to another, especially if one is a traveller or engaged in a similar profession. 

For academics, a map scale is useful to measure exact distances between objects and base their work on that. This is useful in calculating operations such as measuring the demographics of an area, measuring the geographical faults of an area, keeping a note of all physical features of the area and its vegetation, and so on. Measuring and making a note of all detailed features of an area on a map is only possible through map scales. If maps were not drawn to scale then no one would be able to navigate through an unknown place all on their own.