Weather Instruments Maps and Charts - Solutions
CBSE Class 11 Geography
NCERT Solutions
Chapter 31
Weather Instruments, Maps and Charts
1. Choose the right answer from the four alternatives given below.
(i) Which department prepares the weather map of India for each day?
(a) The World Meteorological Organisation
(b) The Indian Meteorological Department
(c) The Survey of India
(d) None of these.
Ans. (b) The Indian Meteorological Department also referred to as Met department, is an agency of the Ministry of Earth Sciences.
(ii) Which two liquids are used in maximum and minimum thermometers?
(a) Mercury and water
(b) Water and alcohol
(c) Mercury and alcohol
(d) None of these.
Ans. (c) Mercury and alcohol.
(iii) Lines connecting the places of equal pressure are called
(a) Isobars
(b) Isohyets
(c) Isotherms
(d) Isohels.
Ans. (a) Isobars.
(iv) The primary tool for weather forecasting is
(a) Thermometer
(b) Barometer
(c) Maps
(d) Weather charts.
Ans. (d) Weather charts.
(v) If there is more humidity in the air, the difference between the readings of a dry bulb and a wet bulb will be
(a) Less
(b) More
(c) Equal
(d) None of these.
Ans. (a) Less.
2. Answer the following questions in about 30 words.
(i) What are the basic elements of weather?
Ans. The basic weather elements include temperature, pressure, wind, humidity and precipitation .
(ii) What is a weather chart?
Ans. Weather charts are the fundamental basis for weather analysis and forecast. The data received from various weather observatories are detailed and in plenty. Therefore, they cannot be incorporated in one single chart unless the coding designed to give the economy of expression is used. These are called synoptic weather charts and the codes used are called meteorological symbols.
(iii) Which instruments are normally available in Class-I observatory to measure the weather phenomena?
Ans. The highest category is Class-I. Typical instrumental facility available in a Class-I observatory consists of the following:
(a) Maximum and minimum thermometers
(b) Anemometer and wind vane
(c) Dry and Wet bulb thermometer
(d) Rain gauge
(e) Barometer
Observations are taken in these observatories normally at 00,03,06,09, 12,15,18,21 hours (Greenwich Mean Time) around the globe. However, for logistic reasons, some of the observatories take limited number of daily observations upper air observation during daytime only.
(iv) What are Isotherms?
Ans. These are lines on a map connecting places of equal temperature at a given time or on average over a given period. Isotherms are commonly used in meteorology to show the distribution of temperature at the Earth's surface oo on a chart indicating constant level or constant pressure.
3. Answer the following question in not more than 125 words.
Discuss how weather maps and charts are prepared and how they are useful to us.
Ans. Weather Maps: A weather map is the representation of weather phenomena of the earth or a part of it on a flat surface. It depicts conditions associated with different weather elements such as temperature, rainfall, sunshine and cloudiness, direction and velocity of winds, etc. on a particular day. These observations being taken at fixed hours are transmitted by code to the forecasting stations. The central office keeps a record of the observations, which forms the basis for making a weather map. The upper air observations which are procured from hill stations, aeroplanes, pilot balloons, etc. are plotted separately. Indian Meteorological Department is getting the weather maps and charts prepared regularly. Meteorological observatories transmit the data to the Central Observatory at Pune twice a day. Data is also collected on ships plying on the Indian seas. A good progress has been made in the field of weather forecasting and observation with the establishment of weather observatories in Antarctica, the International Indian Ocean Expedition, and the launching of rockets and weather satellites.
Utility:
(a) Weather maps help us to predict weather.
(b) Weather forecasting helps farmers, fishermen, soldiers, navigators and pilots in many ways.
(c) Disaster management is not possible without weather maps and charts. (d) Weather maps are also used for research and weather forecasting purposes.
Weather charts : Weather charts are the fundamental basis for weather analysis and forecast. The data received from various weather observatories are detailed and in plenty. As such, they cannot be incorporated in one single chart unless the coding designed to give the economy of expression is used. These are called synoptic weather charts and the codes used are called meteorological symbols.The lines on a weather chart are known as isobars and represent areas of equal pressure.
Utility:
(a) Weather charts provide the primary tools for weather forecasting.
(b) They help in locating and identifying different air masses, pressure systems, fronts and areas of precipitation.
