Experts have designed these Class 7 SST Notes Chapter 2 Understanding the Weather Class 7 Notes for effective learning.
Class 7 Understanding the Weather Notes
Class 7 SST Chapter 2 Understanding the Weather Notes
Class 7 SST Chapter 2 Notes – Understanding the Weather Notes Class 7
→ Predict: To say that something will happen in the future, is to predict.
→ Meteorology: It is the scientific study of atmosphere, weather, and climate. It involves forecasting weather and understanding atmospheric processes.
→ Meteorologists: They are scientists who study the atmosphere and weather patterns. They use various tools to predict and analyse weather conditions.
→ Range of temperature: It is the difference between the maximum and minimum temperatures.
→ Mean daily temperature: It is the average temperature calculated by adding the maximum and minimum temperatures and dividing by two.
→ Ambient: Of the area around; on all sides.
→ Statistics: The practice or science of collecting and analysing numerical data in large quantities.
→ The India Meteorological Department: It is the national agency responsible for weather forecasting, monitoring and research in India. It provides weather updates, warnings and climate data. It was setup in 1875.
→ Rain Gauge: It is used to measure the amount of rainfall. The rainfall is measured in millimetres (mm) or centimetres (cm).
→ Barometer: It is used to measure the atmospheric pressure of an area. The atmospheric pressure is higher near the sea coast and lower down into the mountains. The unit of measurement is millibar.
→ Acclimatise: It means to change to suit different conditions of weather.
→ Wind vane: It is an instrument used to show the direction of the wind. It is used in weather stations, airports, ships and farms to determine wind direction for weather forecasting and navigation.
→ Wind sock: Wind vane on the tarmac (runway of an aeroplane) is called wind sock.
→ Anemometer: It is an instrument used to measure wind speed. It is commonly used in weather stations, aviation and meteorological research.
→ Relative humidity: It is the percentage of water vapour in the air compared to the maximum amount the air can hold at a given temperature.
→ Hygrometer: It is an instrument used to measure relative humidity.
→ Wet and dry bulb thermometers: A larger difference between the dry bulb and wet bulb temperatures indicates low humidity, whereas a smaller difference indicates high humidity.
Understanding the Weather Class 7th Notes
WEATHER AND ITS ELEMENTS
- In winter, when one feels cold and shivers, they wear warm clothes to stay warm.
- Similarly, in summer, when one feels hot, they wear light and cool clothes to stay cool.
WHAT IS WEATHER?
- Weather refers to the atmospheric conditions of a particular place at a specific time.
- It includes various elements like temperature, humidity, wind speed, air pressure and precipitation.
- Weather can change frequently, from day to day or even hour to hour.
- Since ancient times, humans have predicted weather by observing nature.
- Behaviours of birds, ants, squirrels, frogs and pine cones signal upcoming weather changes.
- This wisdom has been passed down and is still used, especially for predicting monsoons.
- Meteorologists help us understand how the elements of weather are measured.
WEATHER INSTRUMENTS
- The meteorologists use different types of instruments to systematically record and monitor the behaviour of different elements of weather.
- These instruments are called weather instruments. Different kinds of instruments are used to measure the different elements of weather.
(a) Temperature
- The temperature of a place is measured using a thermometer.
- There are different types of thermometers.
- Some thermometers simply measure ambient temperature. Others record maximum and minimum temperatures during a day.
- Often coloured liquid is used in thermometers which expand when the temperature increases.
- Nowadays, digital thermometers are used as they are more precise and accurate.
- Unit of measuring temperatures is degree Celsius or degree Fahrenheit.
(b) Precipitation
- Precipitation is any form of water that falls from the atmosphere to the Earth’s surface.
- It includes rain, snow, sleet and hail.
- Rainfall is measured using an instrument called rain gauge.
- Rainfall is measured in centimeters (cm) or millimeters (mm).
(c) Atmospheric Pressure
- Atmospheric pressure is the force exerted by the air on the Earth’s surface.
- It is measured using a barometer and unit of measuring atmospheric pressure is Pascal (Pa) or Millibar (Mb).
- The normal atmospheric pressure sea coast is 1013 mb.
- The atmospheric pressure below lOOOmb means there is a depression.
(d) Wind
- Wind is the movement of air from high-pressure to low pressure areas.
- It is caused by differences in atmospheric pressure and influences weather patterns.
- The speed of the wind is measured using an anemometer.
- The unit of measuring wind is kilometers per hour (km/h) or miles per hour (mph).
(e) Humidity
- Humidity is the amount of water vapour present in the air.
- Humidity also depends on temperature, air pressure, wind and location.
- It affects weather conditions.
- It is measured using a hygrometer and the unit of measuring relative humidity is percentage (%).
WEATHER STATIONS
- These are facilities equipped with instruments to observe and record atmospheric conditions like temperature, humidity, wind speed and air pressure for weather forecasting.
AUTOMATED WEATHER STATIONS
- These are self-operating systems that use sensors to measure and record weather conditions like temperature, humidity, wind speed its directions, precipitation and air pressure without human intervention.
PREDICTING THE WEATHER
- Meteorologists analyse past and present weather data to forecast upcoming weather conditions accurately. It helps in minimising loss of life and property during storms, cyclones and other natural disasters.