Weather and Climate Online Test 8th Social Science Lesson 6 Questions in English

Weather and climate influence man’s activities like what we eat, wear, the house in which we live and work, farming, sailing, and even our play time etc.

Weather is the day today conditions(state) of the atmosphere at any place as regards sunshine, temperature, cloud cover, Wind fog condition, air pressure, humidity, precipitation and such other elements.

Weather refers to short periods like a day, a week, a month or a little longer and as such the weather changes from time to time in a day and one period to the other in a year. The weather is cool in winter and hot in summer.

The average atmospheric conditions are determined by measuring the weather elements for a long period of time which is usually for 35 years.

Scientific study of weather is called Meteorology and the scientific study of climate is called climatology.

The difference in temperature makes the air and water move in currents.

Warm air rises and creates more space for air beneath, while cool air settles down.

Climate is generally defined as the average conditions (state) of the weather of a place or a region.

The Polar regions receive slanting sun’s rays. Hence there is little or no sunlight, thus there is an extreme cold Winters. Vertical sun’s ray’s fall directly on regions around the equator hence the climate is very hot and almost no winters.

Angle of the sun’s rays, the length of daytime, altitude, distribution of land and water bodies, location and direction of mountain ranges, air pressure, winds and ocean currents are the major factors which affect the weather and climate of a region.

Temperature is one of the key elements of weather and climate. The earth and its atmosphere get heated from the sun through insolation.

Temperature varies with time due to changes in the level of radiation which reach the earth surface. This is due to motions of the earth (The rotation and revolution) and inclination of the earth’s axis.

Heat energy from solar radiation is received by the earth through three mechanisms. They are radiation, conduction and convection.

Temperature, rainfall, pressure, humidity and wind are the major elements of weather and climate.

The temperature influences the level of humidity, the process of evaporation, condensation and precipitation. The Earth's atmosphere is heated more by terrestrial radiation than insolation.

Temperature varies both horizontally and vertically. Temperature decreases with increasing height is known as Lapse rate.

The temperature of a unit volume of air at a given time is measured in scales like Celsius, Fahrenheit, and Kelvin.

Meteorologist measures the temperature by the Thermometer, Stevenson screen and minimum and maximum Thermometer.

Atmosphere is mainly heated by outgoing radiation from 2 to 4pm.So the maximum temperature is recorded between 2 and 4 pm regularly and minimum temperature is recorded around 4 am before sunrise.

The average of maximum and minimum temperatures within 24 hours is called mean daily temperature.

Diurnal range of temperature is the difference between the maximum and minimum temperatures of a day. Annual range of temperature is the difference between the highest and lowest mean monthly temperatures of a year.

The distribution of temperature is shown by means of Isotherms. Isotherms are imaginary lines which connect the same temperatures of different places.

The fact that the earth is spherical in shape results in different parts of the earth getting heated differently.

Based on the heat received from the sun, Earth is divided into three heat zones.

Frigid Zone lies between the Arctic circle and the North Pole and between the Antarctic circle and the South Pole.

Temperate zone gets the slanting rays of the sun and the angle of the sun’s rays goes on decreasing towards the poles. This zone experiences moderate temperature.

Torrid zone region receives the direct rays of the sun and gets the maximum heat from the sun. This zone known as the torrid or the tropical zone.

Torrid Zone is a region between the tropic of cancer and the tropic of Capricorn. Temperate zone lies between the Tropic of cancer and the Arctic circle in the Northern Hemisphere and between the Tropic of Capricorn and the Antarctic circle in the southern Hemisphere.

Frigid region also known as Polar region. Since it receives the extremely low temperature throughout the year, these regions are covered with snow.

The highest temperature ever recorded on the earth is 56.7°C (134°F).

The highest temperature was recorded on 10th July 1913 at Greenland Ranch of Death Valley, California, USA.

The lowest temperature ever recorded on the earth is −89.2 °C (−128.6 °F; 184.0 K).

The lowest temperature on earth ever was recorded on 21st July, 1983 at Soviet Vostok Station in Antarctica.

Rain is a liquid water in the form of droplets that have condensed from atmospheric water vapour and then become heavy enough to fall under gravity. Rain is a major component of the water cycle and is responsible for depositing most of the fresh water on the Earth.

Rainfall is high in the equatorial region and decreases gradually towards poles. Rainfall is measured by Rain gauge.

The weight of air above a given area on the earth’s surface is called atmospheric pressure or air pressure.

Meteorologist uses barometer/aneroid barometer to measure the air pressure.

The standard air pressure at sea level is 1013.25mb. At the earth’s surface the pressure is 1.03kg.per.sq cm

The variation in standard atmospheric pressure is found both horizontally and vertically. Based on the level of pressure, it is categorised into low pressure and high pressure.

Isobar is used to show the distribution of air pressure in atmosphere.

Low pressure systems are also called as a depression and cyclones. High pressure system is called anti cyclones

Low pressure area is an area in the atmosphere where the pressure is lower than its surrounding areas. High pressure is an area of atmosphere where the barometric pressure is higher than its surrounding areas.

Low pressure leads to cloudiness, wind, and precipitation. High pressure leads to fair and calm weather.

The highest ever air pressure at sea level was recorded at Agata, Russia on 31st December, 1968.

The highest ever air pressure at sea level recorded was 1083.8mb

The lowest pressure of 870mb was recorded at Typhoon Tip, near Guam, Mariana Island in Pacific Ocean.

The lowest ever air pressure was recorded on 12th October, 1979.

Humans are not sensitive to small variation in air pressure. Barograms are used for recording continuous variation in atmospheric pressure.

Humidity refers to the degree of water vapour present in the atmosphere in gaseous form in particular time and place.

Climatically it is an important constituent of the atmosphere and its quantity depends on the level of temperature. So, the level of humidity decreases towards poles from equator.

Humidity ranges from 0-5 percent by volume in atmosphere.

Specific humidity is a ratio of the water vapor content of the mixture to the total air content on a mass basis. It is expressed in grams of vapour per kilogram of air.

Absolute Humidity is the mass or weight of water vapour present per unit volume of air. It is expressed usually in grams per cubic meter of air.

Generally, warm air holds more water vapour than the cold air.

When relative humidity reaches 100%, the air gets saturated. In this condition the temperature is said to be at dew-point.

Relative humidity is a ratio between the actual amount of water vapour present in the air and the maximum amount of water vapour it can hold at a given temperature. It is expressed as a percentage.

Relative humidity affects human health and comfortness. Very high and very low humidity are injurious to health. It also affects the stability of different objects, buildings and electrical applications.

Hygrometer is used to measure the humidity. (which comprises wet and dry bulb plate side by side in the Stevenson screen)

The horizontal movement of air is called wind. Vertical movement of air is said as air current.

The winds move from high pressure to low pressure. Unlike other elements a wind is made up of a series of gusts and eddies which can only be felt and not seen.

The wind systems are broadly categorized into three as follows 1. Planetary winds 2. Seasonal winds 3. Local winds

Planetary Winds are the ones which blow almost in the same direction throughout the year. So, they are called as Permanent or planetary winds.

Seasonal winds are those which change their direction according to season in a year. They are called as monsoon winds. These wind blow from sea to land during summer and land to sea during winter.

Local winds are the winds blow over a small area only during a particular time of a day or a short period of a year.

Trade winds, Westerlies and polar easterlies are the types of prevailing or planetary winds. Land and sea breezes are example of local winds.

The Beaufort scale is a scale for measuring wind speed. It is based on observation rather than accurate measurement.

The Beaufort scale was developed in 1805 by Francis Beaufort, an officer of the Royal Navy and first officially used by HMS Beagle.

Wind speed is measured by anemometer.

Meteorologist measures wind direction using wind vane or weather cock.

Brazil has a large area where the average wind speed is low. Gabon, Congo and DR Congo in Africa, Sumatra, Indonesia and Malaysia are the least windy places on earth.

Transfer of heat energy from one place to another through the substances that are in direct contact with each other is called conduction.

Eddies are the wind circulation that develops when the wind blows over or adjacent to rough terrain, buildings, mountains or other obstructions.

Meteorograph or triple register is an instrument which records wind speed and direction, sunshine and precipitation. It also provides graphic representation.

With decreasing air pressure, the availability of oxygen to breath also decreases. Aircraft create artificial pressure in the cabin which makes the passengers remain comfortable while flying.

Earth's atmosphere is a layer of gases surrounding the planet earth and retained by the earth's gravity. It contains about 78% nitrogen, 21% oxygen, 0.97% argon, 0.03% carbon dioxide and 0.04% trace amounts of other gases and water vapour.

Wind rose is a diagram used to depict the direction and periods (No. of days) of prevailing winds on map.