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VIII SS T1 WEATHER AND CLIMATE BOOK BACK ANSWERS
UNIT 2
WEATHER AND CLIMATE…..
EVALUATION:
I. Choose the correct answer
1. Earth's atmosphere contains about ______________ percentage of nitrogen and oxygen.
a) 78% and 21% b) 22% and 1%
c) 21% and 0.97% d) 10% and 20%
Ans: a) 78% and 21%
2. ______________is generally defined as the average conditions of the weather of a place or a region.
a) earth b) atmosphere
c) climate d) sun
Ans: c) climate
3. The earth receives energy from ______________ .
a) current b) electromagnetic radiation
c) waves d) heat
Ans: b) electromagnetic radiation
4. Which one the following represents places with equal amount of rainfall ______________
a)isotherm b) isohel
c)isobar d) isohyets
Ans: d) isohyets
5. ______________is used to measure the humidity.
a) anemometer b) barometer
c) hygrometer d) thermometer
Ans: c) hygrometer
II Fill in the blanks
1. ______________ refers to the condition of atmosphere for a short period of time.
Ans: Weather
2. The scientific study of weather is called ____.
Ans: Meteorology
3. The highest temperature ever recorded on the earth is ______________.
Ans: 56.7℃
4. ______________ is a ratio between the actual amount of water vapour and the
maximum amount of water vapour the air can hold.
Ans: Relative humidity
5. _____________ and_____________ are measured by anemometer and wind vane
Respectively.
Ans: Wind speed, Wind direction
6. __________ are imaginary lines which connect the same temperatures of different
Places.
Ans: Isotherms
III Match the following
1. Climate - Long Term Changes
2. Isonif - Equal Snowfall
3. Hygrometer - Humidity
4. Radar - Locating and Tracking Storms
5. Low Pressure - Cyclone
IV State whether the following statements are True or False
1. The atmosphere is a layer of gases surrounding the planet.
Ans: True
2. The Scientific study of weather is called Climatology.
Ans: False
3. Isohel refers equal sunshine.
Ans: True
4. Humidity is calculated by Aneroid Barometer.
Ans: False
V Answer briefly
1. Define ‘weather’.
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.
2. What is insolation?
The earth and its atmosphere get heated from the sun through insolation. Insolation is the solar radiation that reaches the earth’s surface.
3. What is meant by atmospheric pressure?
The weight of air above a given area on the earth’s surface is called atmospheric pressure or air pressure. The air pressure is measured by Barometer
4. Write a short note on “Planetary winds”
Planetary Winds are the ones which blow almost in the same direction throughout the year. So, they are called Permanent or planetary winds.
5. What are “Isolines”?
Isolines are lines drawn to link different places that share a common value. The prefix 'iso' is a Greek word meaning equal. So, an isoline is a line joining equal points.
VI Distinguish between
1. Weather and climate.
Weather:
Weather is the day to day condition of the atmosphere at any place
Refers to short periods like a day, a week, a month etc.,
Sunshine, temperature, cloud cover, wind, fog condition, air pressure, humidity, precipitation are some weather elements.
Climate:
Average condition of the weather of a place or a region.
Determined by measuring weather elements for a long period of time usually for 35 years
Latitude, Altitude, direction of winds, distance from the sun, Ocean currents are some of the factors determining climate.
2. Absolute and relative humidity.
Absolute Humidity
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.
Relative humidity
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.
3. Permanent and seasonal winds.
Planetary Winds
Planetary Winds are the ones which blow almost in the same direction throughout the year.
They are also called as Permanent or planetary winds
Example: Trade winds, Westerlies and polar easterlies
Seasonal winds
Seasonal winds are those which change their direction according to season in a year. They are also called monsoon winds.
Example: North east monsoon winds
VII Give reasons
1. The Weather and climate in different regions vary.
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. The earth is spherical in shape. So, the sun’s rays fall unevenly on the earth’s surface. The Polar regions receive slanting sun’s rays. Hence there is little or no sunlight, thus there are extreme cold winters. Vertical sun’s rays fall directly on regions around the equator, hence the climate is very hot and almost no winters. 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.
2. Temperature decreases with increase in altitude.
Temperature is one of the key elements of weather and climate. 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.
3.Mountain climbers carry oxygen cylinders while ascending peaks.
With decreasing air pressure,the availability of oxygen to breath also decreases. Mountain climbers use bottled oxygen when they ascend very high peaks. They also take time to get used to the altitude as the quick move from high pressure to low pressure can cause decompression sickness.
VIII Answer in a paragraph
1. How is temperature measured?
The temperature of a unit volume of air at a given time is measured in scales like Celsius, Fahrenheit, and Kelvin. Meteorologists measure the temperature by the Thermometer, Stevenson screen and minimum and maximum Thermometer.
The energy received by the earth through insolation is lost by outgoing radiation.
Mean Temperature
The average of maximum and minimum temperatures within 24 hours is called mean daily temperature [(87o F+73o F)/2=80o F]. 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.
2. Write about the wind and its types.
Wind The horizontal movement of air is called wind.
The wind systems are broadly categorized into three as follows.
Planetary winds
Seasonal winds
Local winds
1. Planetary Winds
Planetary Winds are the ones which blow almost in the same direction throughout the year. So, they are called Permanent or planetary winds. Trade winds, Westerlies and polar easterlies are the types of prevailing winds.
2. Seasonal winds
Seasonal winds are those which change their direction according to season in a year. They are called monsoon winds. These winds blow from sea to land during summer and land to sea during winter.
3. Local winds
Local winds are the winds that blow over a small area only during a particular time of a day or a short period of a year. Land and sea breezes are examples of these winds.
3. List out the weather elements and associated measuring instruments.
Temperature, rainfall, pressure, humidity and wind are the major elements of weather.
a) Temperature:
The degree of heat present in the air is termed as temperature. The temperature influences the level of humidity, the process of evaporation, condensation and precipitation. The temperature is measured in scales like Celsius, Fahrenheit, and Kelvin.
b) Rainfall:
Rain is a major component of the water cycle and is responsible for depositing most of the freshwater on the Earth. It is the source of water for all purposes. Rainfall is measured by Raingauge.
c) Air Pressure:
The weight of air above a given area on the earth’s surface is called atmospheric pressure or air pressure. The air pressure is measured by Barometer. The standard air pressure at sea level is 1013.25mb.
d) Humidity:
Humidity refers to the degree of water vapor present in the atmosphere in gaseous form in particular time and place.
Humidity is expressed in Absolute Humidity and Relative humidity
e) Wind:
The horizontal movement of air is called wind. The winds move from high pressure to low pressure.
Winds get their name from the direction from which they blow i.e, wind blows from south west is called southwest wind.
