The globe of the earth is divided into three layers namely (a) The Earth’s crust, (b) Mantle and (c) Core.The Earth’s Crust : The outermost layer of the earth is called as the earth’s crust. It is about 30 km thick. In the region of continents it is thicker but at the floors of oceans […]
Water is a peculiar liquid as it can exist in three states namely solid state as ice, liquid states as water and gaseaus state as water vapour. In this chapter we discuss about humidity and rainfall.Water Vapour : Water is continuosly evaporating from seas, rivers, lakes, ponds etc. due to the heat of the sun.
Our atmosphere is a blanket of large amount of air. The pressure at any point on the earth’s surface due to the weight of the column of air is also quite large. It is almost equivalent to the weight of three elephants on our body or 15 pounds per square inch.Measurement and Units of PressureA
Weather : The prevailing atmospheric conditions—temperature, pressure, humidity, wind velocity and so on defines the weather. The study of weather is called meteorology carried out by meteorologists.Climate : Climate is the average weather conditions of a region over a long period or the climate is the long term or integrated manifestation of weather.Climate Controling FactorsClimate
Atmosphere : The blanket of air that covers the Earth is known as the atmosphere.The atmosphere goes up to about 1000 km from the surface of the Earth. 99% of the total mass of the atmosphere is contained within 32 km. The atmosphere gases are held by the gravitational pull of the Earth.Composition of the
Rotation of the Earth1. An imaginary line from west to east is taken as axis of the earth. Turning the earth from west to east is called the rotation of earth. Rotation makes the sun to rise every day in the east and set in the west.2. The earth spins around is aris west to
Longitudes extent from the north pole to south pole. These are the north-south lines. All meridians are halves of great circles.Latitudes are the east-west lines. Only one latitude, the equator, is a great circle.Relative location : It tells a particular place with respect to another place.Absolute location : It indicates position based on the coordinates
About 71% of earth is covered with water and 29% is the land mass.There are 7 continents—1. Asia (largest), 2. Africa, 3. North America, 4. South America, 5. Antarctica,6. Europe, 7. Australia (Smallest) OceansThere are four oceans. In order of decreasing size, they are:1. Pacific Ocean, 2. Atlantic Ocean, 3. Indian Ocean, 4. Arctic Ocean.The
The age of the earth has been estimated as 4.6 billion years. Many methods like radioactive dating, fossil records etc. have been used to determine the age of the earth. Scientists have also discovered that life on earth started some 570 million years ago. The first 345 millions years saw the development of marine life.
Space means outer space or the region beyond earth. It is that portion of the universe which is beyond the immediate influence of earth. The study of region beyond earth and the objects present in it is called space science.Space science is used for continuous weather monitoring and weather forecasting on the earth. This is
Solar System Solar System : The sun, nine planets, moons of the planets, meteors, meteorites, comets, etc. are all the members of solar system. All the members of the solar system revolve round the sun.Some Facts about Solar System(a) The sun is the centre of the solar system. It is a star and nearest to
Many scientists have made many researches in the field of botany. A brief description of these is given below. Some Important Things to know
Autotroph : It is defined as an organism that can make organic molecules from inorganic nutrients.Continent Drift : The drift of continents with respect to one another over the plates in the earth’s interior.Extinction : Disappearence of species from the earth is called extinction, e.g. Dodo became extinct from Mauritius.Fossil : The remains of ancient
The world in which we live constitute our environment. High population and industrialisation has polluted the environment and has caused many problems. This chapter describes environment and its pollution.Environment : The physical and biological world where we live is called our environment. It has three components : (i) Physical surroundings (ii) Living organisms (iii) Meteorological
Forest : A forest is a biotic community having trees, shrubs and any other woody vegetations usually with a closed canopy.Economic importance of Forests1. Forests conserve fertility of the soil, 2. Cause rains, 3. Give wood, paper, medicines, rubber, resins, gums, shellac, natural dyes, lac, honey, wax, cork, 4. Provide fuel wood, 5. Provide shelter