5th Standard Social Science Term-I
Atmosphere
Biosphere
Biosphere is the combination of Lithosphere, Hydrosphere and Atmosphere that can support life.
🌑 Lithosphere - Land on Earth
🌑 Hydrosphere - Water on Earth
🌑 Atmosphere - Air on Earth
🌑 Biosphere - Life on Earth
Atmosphere
Atmosphere is the envelope of air around the Earth.
Weather
Weather is a day to day conditions of atmosphere at any place in regard to temperate weather condition of a vast area over more than 30 years.
Climate
Climate is the average weather condition of a vast area over more than 30 years.
When is World Environment Day observed?
Atmospheric Layers
We know that the gravitational force increases near the Earth and decreases as we go higher. As a result the density of air also differs and can be found in five layers called Troposphere, Stratosphere, Mesosphere, Thermosphere and Exosphere. All weather changes occur in the Troposphere. The study of weather is called Meteorology.
The word climate is derived from the Greek word called clima.
World Meteorological Day - March-23
World Ozone Day - September-16
Farenheit, Celsius and Kelvin are the units used to measure temperature.
Solar Radiation
The sun is the only source of light to all the planets in the solar system. The land, water and air in our planets receives heat from the sun. The Earth receives heat energy from the Sun in the form of radiation. It is called solar radiation.
Elements of Climate
1) Temperature 2) Pressure 3) Wind 4) Clouds 5) Rainfall
1) Temperature
🌑 Land - Conduction
🌑 Water - Convection
🌑 Atmosphere - Terrestrial radiation
The earth has the capacity to reflect the sun's rays. The temperature is not same every where. Latitude, altitude, distance from the sea, position of the mountains are some of the factors that determine the temperature of a place.
Let US KNOW
The imaginary lines drawn horizontally on the Earth surface from West to East are called latitudes.
The imaginary lines drawn vertically on the Earth surface from North to South are called longitudes.
Latitudes and longitudes help us to locate a place correctly.
Why does heat vary from morning to evening?
It is because of the sun's rays.
The land is divided into various heat zones according to the fall of sun's rays on the surface of the Earth.
🌑 The zone between Tropic of Cancer and Tropic of Capricorn is called Tropical or Torrid zone, where the sun's rays fall vertically.
🌑 The zone between 231/20N to 661/20N latitude and 231/20S to 661/20S latitude which receives slanting rays of the sun is called Temperate zone.
🌑 The zone which receives the extreme slanting rays of the sun and experiences extremely low temperature is called Frigid zone.
2) Pressure
When the temperature increases, pressure decreases and when the temperature decreases, pressure increases.
The average pressure of wind at sea level is 1013 mb (milli bar)
The instrument which is used to measure the pressure of the wind is Barometre.
The instrument which is used to measure the speed of the wind is Anemometre.
The instrument which is used to measure the direction of the wind is Wind Vane.
3) Wind
The air which moves horizontally from high pressure area to low pressure area is called wind. Air never moves in one direction. It differs from place to place and time to time. This is due to the rotation of the earth.
Wind energy is a form of renewable energy. Wind turbines converts the kinetic energy into mechanical energy. A generator can convert mechanical energy into electrical energy.
Loo Wind
Loo is a strong, dusty, hot and dry summer wind which blows over the North Western India during the months of May and June.
Different types of Wind
Planetary Wind
This wind blows in the same direction throughout the year.
Monsoon Wind
The word monsoon is derived from the Arabic term 'mausim' which means season. Monsoon wind is the seasonal wind.
Types of Monsoon winds in India
🌑 South West monsoon wind 🌑 North East monsoon wind.
Sea Breeze
Sea breeze blows from sea to land in the evening.
Land Breeze
Land Breeze blows from land to sea in the morning.
Local Wind
Local wind affects the weather.
🌑 Warm local wind - North West India, E.g. Loo
🌑 Cool local wind - North East India E.g. Norwesters.
Jet Streams
Air currents in the upper layers of atmosphere is known as Jet streams. It could determine the arrival and departure of monsoon winds in India.
Cyclone (Hurricane)
Cyclone changes its position and direction with time to time. The speed of wind also changes with time. It gives heavy rainfall.
4) Clouds
Clouds are large collection of very tiny droplets of water. These are divided into four types on the basis of appearance and height. They are :
🌑 Cirrus clouds 🌑 Stratus clouds
🌑 Cumulus clouds 🌑 Nimbus clouds
Cirrus Cloud
Cirrus cloud appears like a silver grey fish at a very high altitude in the sky. These may not give rain.
Stratus Cloud
Stratus cloud is grey in colour and are spreadout. They may give small shower.
Cumulus Cloud
Cumulus cloud looks like a puffy white cotton and gives convectional rainfall. These clouds are associated with rainfall, lightning and thunder.
Nimbus Cloud
Nimbus cloud appears as dark or grey in colour. It gives heavy rainfall. It is called vertical or rain clouds.
5) Rainfall
Condensation of the water vapour causes rainfall. Rain water must be saved and not be wasted.
Convectional Rainfall
During summer solar insolation takes place in land and water evaporates from lakes, ponds, seas, oceans and vegetations. Due to this, a heavy rainfall with lightning and thunder occurs in the evening for a short period.
The natural materials and living things, including sunlight are called natural environment.
Orographic Rainfall
When the moisture laden winds from the sea rises as it moves over a mountain range; it becomes cool and causes heavy rainfall. The opposite side of the mountain is called Leeward side. It receives very little rainfall.
Cyclonic Rainfall
The warm air from the hot area is heated and moves upwards. Hence a low pressure are is developed and it attracts air from high pressure area. Owing to Earth's rotation a circular motion of winds develop. It gets cooled and brings heavy rainfall.
Rain Water Harvesting
Rain water harvesting is a technique of collection and storage of rainwater into natural reservoirs or tanks, or the infiltration of surface water into subsurface aquifers (before it is lost as surface runoff). One method of rainwater harvesting is Rooftop Harvesting.
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