Weather

Question 1 Name few activities of our daily life which are planned according to the weather on a day?

Question 2 Define the term humidity? How is it expressed?

Question 3 Name the instrument used to measure the rainfall at a place?

Question 4 What is meant by weather? Name the elements which determine the weather of a place?

Question 5 What produces weather? Why does weather changes so frequently?

Question 6 When are the maximum and minimum temperature likely to occur during a day?

Question 7 Why in summers we feel so miserable in the afternoon and comparatively comfortable in the early morning?

Question 8 Who are meteorologists?

Question 9 What is weather forecasting?

Question 10 What does weather reports tell us?

Activities related to Weather on a day

1) During the summer days, we wear light coloured clothes because the weather is hot.

2) In winter, we prefer to wear dark coloured clothes because the weather is cold.

3) If there are clouds in the sky on a particular day, we usually take an umbrella (or raincoat) with us.

4) If we are planning to go to a hill station for holidays, then we always take along woollen clothes with us because the climate on the hill stations is always cold.

5) If we are going to a coastal area (sea-side area), then we do not need woollen clothes because the climate there is not cold.

Weather and climate are two different things.

 

Humidity

Humidity is a measure of water vapour (or moisture) in air.

1) When the amount of water vapour in the air is high, we say humidity is high and the air feels moist (or damp). Under these conditions, the sweat from our body does not evaporate readily and we feel hot and uncomfortable.

2) If the amount of water vapour is low, we say the humidity is low. When the humidity is low, the air feels dry. Under these conditions, the sweat from our body evaporates readily and we feel cool and comfortable.

Humidity of air is expressed as a percentage (%). A humidity of 100 per cent (100%) at a particular temperature means that the air is saturated with water vapour at that temperature (which means the air is holding the maximum amount of water vapour for that temperature).

Rainfall is measured by an instrument called rain gauge. Rain gauge is basically a measuring cylinder with a funnel at the top to collect rainwater. Rain gauge measures the rainfall at a place in the unit of millimetres (mm)

Weather

1) If the temperature of air (or atmosphere) around us on a particular day is high, we say that the weather is ‘hot’ today.

2) If the temperature on a day is low, we say that the weather is cold.

3) If there is lot of water vapour (or moisture) in the air, we say that the weather is too humid.

4) If there is rain, we say the weather is ‘rainy’ today

5) If a lot of wind starts blowing on a day, then we say that the weather is very windy today.

Weather is actually the condition of the atmosphere (or air) around us at a particular time. The day-to-day condition of the atmosphere at a place and time with respect to the temperature, pressure, humidity, wind speed and wind direction, sunshine, clouds, rainfall (or snowfall), etc., is called weather at that place at that time.

The various factors which decide weather at a place are called elements of weather.

The major elements of weather at a place are temperature, pressure, humidity, wind speed and wind direction, sunshine, clouds, and rainfall (or snowfall)

Some types of weather are: hot, cold, sunny, cloudy, foggy, dry, humid, windy and rainy.The weather at a place changes day after day and week after week.

Weather is never constant anywhere.Weather affects many of the things we do.

For example: we wear the clothes according to the prevailing weather ; we eat food depending on weather and we make our travel plans keeping the weather in mind.

What Produces Weather

Weather is produced by the heat of the sun and the effect it has on the atmosphere. The heat energy of the sun absorbed and reflected by the earth’s surface, oceans and atmosphere, plays an important role in determining the weather at any place.

For example: The sun’s heat causes water from the ocean and land to evaporate. These water vapour rise high-up in the atmosphere, get cooled, condense and form clouds in the atmosphere which produce rain leading to rainy weather. Similarly, heat from the sun heats the earth’s surface. The hot surface of earth heats the air near it. This hot air (being lighter) rises up creating an area of low pressure. Air from high pressure area moves towards the low pressure area. The air moving from high pressure area to low pressure area is called wind. So, it is the sun’s heat which causes wind to blow and gives us windy weather.

The weather changes so frequently because the condition of the earth’s atmosphere keeps changing frequently due to the various effects produced by the sun’s heat.

 

Maximum and Minimum Temperatures

The highest temperature reached during a day is called the maximum temperature and the lowest temperature during the day is called the minimum temperature.

The maximum and minimum temperatures reached during a whole day are recorded automatically by a special thermometer called Maximum-and-Minimum thermometer.

1) The maximum temperature of the day generally occurs in the afternoon.

2) The minimum temperature of the day generally occurs in the early morning.

During summers, we feel miserable in the afternoon because the maximum temperature of the day is reached in the afternoon (making the surroundings very hot and unbearable)

We feel comparatively cool and comfortable in the early morning during summers because the minimum temperature of the day is reached in the early morning (making the surroundings somewhat cooler)

All the seven days of the week do not have the same maximum and minimum temperatures at a place. The maximum and minimum temperatures keep on changing day by day.

By monitoring the atmospheric conditions such as temperature, pressure, humidity, wind speed and wind direction, sunshine, cloud formations, rainfall (or snowfall), etc., it is possible to predict the coming weather in advance.

Prediction of weather in advance is called weather forecasting.

Weather experts use the various types of data collected by Earth Stations in different parts of the country as well as by the Satellites orbiting high up in the sky to predict weather (or forecast weather) well in advance.

The scientific study of weather is called meteorology.

The scientists who study and forecast weather are called meteorologists.

Weather Reports

The daily weather report carries information about the temperatures, humidity and rainfall during the past 24 hours. It also gives the timings of sunrise, sunset moonrise and moonset. The weather report also predicts the weather for the day.

For Example: Max 33°C(+3) / Min16°C (+2) 

Moonset : Monday -9.30 am

Moonrise : Tuesday -11.55 pm

Sunset : Monday -5.34 pm

Sunrise : Tuesday -6.36 am

Clear sky, mist in the morning, Max and Min temperature  will be around 33 °C and 17 °C

Max humidity on Sunday 82 % and min 29%

 

(1) The weather report tells us that the maximum temperature during the past 24 hours was 33°C (The figure +3 in brackets means that this maximum temperature is 3°C above normal). The minimum temperature during the past 24 hours is shown to be 16°C (The figure +2 in brackets means that this minimum temperature is 2°C above normal)

(2) The weather report tells us that the moon will set on Monday at 9.30 pm and moon will rise on Tuesday at 11.55 pm. It also informs us that the sun will set on Monday at 5.34 pm and the Sun will rise on Tuesday at 6.36 am.

(3) Sky will remain clear which means no clouds but there will be mist in the morning. The maximum and minimum temperatures predicted for the day are around 33°C and 17°C.

(4) The maximum humidity recorded in the past 24 hours was 82 per cent and the minimum humidity was 29 per cent.

(5) Since rainfall does not occur every day, so no rainfall has been recorded in the above weather report during the past 24 hours

The times of sunrise and sunset also change during the year. During summer, sunrise is early and the sunset is late. Due to this, days are longer in summers and nights are shorter. During winter the sunrise is late but the sunset is early. Due to this, days are shorter in winter but nights are longer.