General knowledge (GK) section of competitive examinations is an important section of subject testing.Hence preparing adequately for it is an essential part of Test preparation.One of the advantages of preparing for this part of the test is that it allows lot of flexibility in the preparation in terms of study material available for it; it is available anywhere and everywhere in the form of newspaper supplements, GK books and books of general reading.
GK, as tested in competitive tests, covers all general areas of knowledge viz. History, General Science, Economics, Geography, Polity and others. To facilitate easy assimilation of such knowledge on a regular basis, Synergy Tests & Careers magazine will provide to test-takers easy-to-understand informative long type passages as well as objective type material covering relevant topics on each of the abovecited subjects. The study material presented here will be simple and straight-forward GK-content to facilitate your easy reading and grasping. Go ahead, happy reading!
1.The seven continents of the world are
2.Poles, Longitudes and Latitudes
Our earth, as a global planet, has at its two spherical ends, designated pole areas called as the North Pole and South Pole. In between these two poles an imaginatory line called ‘Equator’ is drawn around the globe at the centre. Thus earth sphere is divided into two equal hemisphere parts, namely Northern Hemisphere and Southern Hemisphere.
A set of imaginary lines drawn on the globe joining the north and south poles are called the meridians of longitude. The line drawn at 0° passing through the Royal observatory situated in Greenwich new London (U.K) is called the Prime Meridian. All other Lines drawn passing through various places parallel to this Prime Meridian to the east or west of it are normal meridians and the longitude of a plane is the arc measured in degrees of such parallel lines with the Prime Meridian.
Prime Meridian is a zero degree line passing through the Greenwich Royal Observatory in London, UK. Latitudes are the ones passing through a place measured in degrees measured north or south of meridian between that place and the equator at zero degree.
The latitudes range from 0° at the equator to 90° north or south at the poles.
An ‘international nautical mile’ is defined as equivalent to 1852 international metre. It is proved that one nautical mile very closely approximates to the average length of one minute of latitude.
Each rotation of earth on its axis takes 23 hours 56 minutes and 4.09 seconds.
The velocity of rotation of an object on the earth’s surface at the equator is about 1700 km per hour and it decreases towards the poles.
Earth’s average orbital rotational velocity is 29.79 km/sec.
One revolution is completed in 365 days and six hours.
Eclipses: The total or partial obscuration of light from a celestial body as it passes through the shadow of another body is known as eclipse.
The solar system-The sun and the eight planets and other heavenly bodies that revolve around it constitute the solar system.
Geoids: The geoid is the theoretical shape of the earth based on estimates of its mass, elasticity and speed of rotation, ignoring its surface irregularities.
Based on certain astronomical observation made by French astronomer, Jean Richer, it is revealed that the true from of the earth is not a perfect sphere.
Great circle: It is a circle on earth’s surface, the plane of which passes through earth’s centre, cutting it into two equal halves.
Small circle: It is made by a plane passing through the globe any-where except through the centre.
The Tropic of Cancer and the Tropic of Capricorn are examples of small circles.
Summer Solstice: On June 21, the earth is so located in its orbit that the sun is overhead on the Tropic of Cancer.
The northern hemisphere is tipped towards the sun, having the longest day, while the southern hemisphere is tipped away from the sun, having the shortest day.
The sun is overhead on the Tropic of Capricorn resulting in the shortest day in the northern hemisphere.
Equinoxes: Two days in a year when day and night are equal throughout the world are equinoxes, namely 23rd September and 21st March.
Winter Solstice: On December 22, the earth is in an equivalent position on the opposite point is its orbit; so the southern hemisphere is tipped towards the Sun and the northern hemisphere away from it.
Time and Longitude
One hour of time is equivalent to 15 degree of longitude.
This also means that 1 degree of longitude is covered every 4 minutes during the daily rotation of the earth.
Most countries adopt a standard time as per the International Meridian Conference of 1884, held in Washington.
The Standard time in India is the local time of a place at longitude near Allahabad.
International Date Line
- The 180th meridian was designated the International Date Line by the IMC held in Washington D.C., in 1884.
- Counting from Greenwich Meridian, the date immediately east of this line is one day ahead or 12 hours faster than the west.
- The moon is earth’s only satellite with a diameter of about 3480 km and a mass of about 1/81 that of earth.
- The mean distance between the earth and the moon is about 385000 km.
- The time taken by the moon to complete one revolution around the earth is 27 days. 7 hours, 43 minutes and 11.6 seconds.
- The moon at all times keeps the same side towards the earth. This means it rotates on its axis exactly once in each side-real month.
- Like the earth, half of the moon’s surface is always illuminated by the Sun’s rays.
Structure of Atmosphere
- Trophosphere: It is the lower most atmospheric layer extending from about 8 km at the poles and 16 km at equator.
- It is characterised by almost uniform decrease of temperature with a rise in altitude (about 10C per 165 metres)
- Stratosphere: The second layer of atmosphere is called stratosphere.
- The level at which the troposphere gives way to stratosphere is called tropopause.
- The upper limit of this layer is called stratopause.
- Within the stratosphere, temperature increases from about 600C tropopause to about 00C at stratopause
- Ozone is produced in tropical and mid latitudes of stratosphere.
- The stratosphere provides ideal conditions for flying aeroplanes.
- Mesosphere: It is the atompsheric layer extending between the stratopause (at an altitude of about 50 km) and mesopause-the upper limit of mesosphere (at about 80-90 km).
- Within mesosphere, the temperature decreases with altitude from about 00C at stratopause to about 1000C at mesopause.
Thermosphere is the uppermost layer of the atmosphere, extending from the mesosphere at an altitude of about 85 km to 400 km of the atmosphere.
- Within it, the temperature increases with altitude from about 1000C at the mesosphere to over 1500C.
- Exosphere: It is the boundary between the earth’s atmosphere and the interplanetary space.
- The magnetosphere: It is the area surrounding the earth extending to about 60,000 km on the side facing the Sun and more on the opposite side.
- It is the radiant energy that reaches the surface of the earth from the Sun. The Sun emit’s a wide variety of energy waves from very short X-rays to longer infrared rays.
- Only about 1 part in 2000 million of the total of Sun’s radiation reaches the earth, it is essential for the sustenance of life here.
Tropical Rain Forests
- Average temperature about 270C. Annual rainfall-about 250cm. Characterised by high annual temperature and heavy rain fall, this climate type occurs in the belt 00 to 250 North and South.
- Areas-Amazon Basin, Congo Basin, Indonesia. High temperature is due to high humidity, little air movement.
- Monsoon: Annual average temperature- about 260C. Highest temperature in May before summer, rainfall-300 cm, annual.
- This type occurs in western Guinea coast of Africa, South eastern Asia, Eastern Amazon valley, West Indies and Guiana Coast lands of South America.
Tropical Savannah or Sudan
- Annual average temperature about 230C. Annual rainfall about 160 cm.
- Area-Columbia, Guianas, north of Amazon in South America, Burma, Thailand, Northern Australia, Vietnam and Venezuela.
Tropical and Sub-tropical Deserts
- Average annual temperature is 380C; annual summer temperature is 400C, annual winter temperature is 150C.
- Areas-Arabia, South-West Africa, Central Australia, the Thar, The Sahara and South-Western USA.
Tropical and sub-tropical steppe: Average annual temperature is 21°C. Rainfall-small and highly variable. Areas-Arabia, southern Australia, southern Iran, north-western Mexico and north western India.
Humid Meso-thermal or Warm Temperate
- This type is classified into the following sub-groups.
- Mediterranean Type: Average annual temperature is 16°C. Average winter temperature, 10°C, average summer temperature 25°C. Annual rainfall is 40-60 cm. This type is classified into the following sub-groups.
Areas-south-western and south-eastern tip of Australia, Central California, Central Chile, Mediterranean Sea, southern tip of South Africa.
- China type: Annual average temperature is 19°C, annual rainfall 120 cm. Areas-Argentina, eastern coal belt of Australia, southern Brazil, China, Japan, south-east U.S.A. and Uruguay.
- West European type: Annual average temperature is 10°C, annual winter temperature 7°C, annual summer temperature is 15°C. Rainfall occurs throughout the year.
Areas-North America, South America, South-eastern coastal strip of Australia, Western Europe.
- Snow or Humid Micro-Thermal of Taiga: Average temperature of Taiga: Average temperature annual 5°C, winter 3°C, summer, 13°C. Total annual rainfall less than 50 cm. Extends in two large belts in east-west direction from Alaska to New found land in North America from Norway to Kamchatka Peninsula in Eurasia.
- Ice or Polar or Tundra: Annual temperature-summer 10°C, winter, below 0°C.
- Undifferentiated Highland Types: Covers the Andes Mountains, a small part of Alps, the Himalayas, the Rockies and the Tibetian plateau.
- Tropical Desert: Mostly situated between 15°N and 30°S and between 15°N and 30°S. They lie on the western side of land-masses except for Africa where they extend from coast to coast, linking up with the Asian deserts. The chief regions are Sahara (N. Africa), Arabia, parts of Iran, Iraq, Syria, Jordan and Israel, parts of Pakistan, central Australia Namib Desert (S.W. Africa), Atacama (coastal Peru and N.Chile), S. California, N.Mexico and parts of Arizona (N.America). The most common plants are cacti, thorn bushes and coarse grasses.
- Mid-Latitude Deserts: These are situated in the interior of continents of Asia and North America, 30° to 35° latitude. Aridity and a great annual temperature with extremes of winter cold mark the region. In North America these deserts are found in basins surrounded by the Rockies. In South America the Patagonia desert lying to the east of the Andes is an example.