HOW AND WHEN IS THE MAXIMUM & MINIMUM TEMPERATURE OF A DAY RECORDED?
Every day, all the news channels show the maximum and minimum temperatures of various cities
. But very few know at what time is the maximum and minimum temperature recorded in a day.
I have asked this question to my students and my friends. Many answered it wrong.
Even, I also came to know only after completing my studies and I don’t hesitate to accept it. Generally, people think that the answer would be 12;00 noon for the maximum and 12 midnight for minimum.
That is the time when the sun is over head (12:00 noon) or on the other side of the earth (12:00 p.m). But, this is not the correct answer.
MEASURING MAXIMUM TEMPERATURE
Maximum temperature is recorded between 2:30 p.m. to 3:30 p.m. Similarly, the minimum temperature is recorded just before the sun rise. Surprised by the answer. Now let’s know the reason. https://shapingminds.in/pressure-belts-and-wind-system/ When the sun rises, the sunlight starts falling on the earth. The earth starts absorbing the heat. At 12:00 noon, the sun is very bright and rays fall straight on the earth. In other words vertical rays fall on the earth at 12: noon. Now also the earth continues to absorb the heat received from the sun. The process of heating and absorbing continues as long as the sun is in the sky. In coming solar radiation which is received by the earth is called Insolation. ( IN+SOL+LATION means in coming of the solar radiation.) So, the earth absorbs the heat from the sun for almost 12 hours. From sunrise at 5:30 a.m. to sun set at 5:30 p.m.
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WHY MAXIMUM TEMPERATURE IS BETWEEN 2:30 TO 3:30 P.M?
You have just now read about the heat absorbed by the earth. But, it is the matter of give and take. Have you ever thought where does the heat absorbed by the earth go? The earth not only receives the heat from the sun but simultaneously also returns the heat back to the atmosphere. This process of give and take continues. At 12:00 noon, there is no doubt that the rays are straight and harsh which heats the earth’s surface to its maximum. But the earth continues to return. Between 2:30 to 3:30 p.m, both, the heat from the sun and the heat returned by the earth takes the temperature of the atmosphere to it’s maximum. That is why, the maximum temperature is recorded between 2:30 to 3:30 p.m.
EXPERIENCE IT PRACTICALLY- THE MAXIMUM TEMPERATURE
Everyone has experienced it practically. Also read about global warming .During the extreme summer afternoon, just remove your curtains and look outside at 12:00 noon and at 3:00 p.m. You will see the difference. People those who go to the market during summer, try to return back by 12:00 noon. Because, after 12:00 noon, the heat becomes unbearable especially in the interiors of India.
WHAT ABOUT MINIMUM TEMPERATURE ?
Have you ever boiled milk or water at home? Boiling milk (2 liters) takes almost 10 to 15 minutes. But, does it take the same amount of time in cooling also? Can you keep boiled milk in the refrigerator just after 15 minutes? No. Why? This is the answer to your question.
LET’S UNDERSTAND MINIMUM TEMPERATURE
As mentioned above the earth absorbs the heat from the sun for almost 12 hours. From sunrise at 5:30 a.m. to sun set at 5:30 p.m. Even when the sun sets, the earth doesn’t cool down. The earth keeps on returning the heat back to the atmosphere. By early morning, the earth is able to return the heat completely. The surface of the earth cools down. The air which is in contact with the surface of the earth also cools down and we start feeling cold early in the morning. Therefore, the minimum temperature is always recorded just before the sunrise.
IS IT TRUE FOR ALL SEASONS?
No. There are many factors on which the maximum and minimum temperatures depend. https://youtu.be/UNgGZNQ9SLc In a day any time there can be maximum and minimum temperature. Therefore, Meteorologists have to observe the temperature for all 24 hours. It is possible that till morning 10:00 O’clock, it was bright sunny, but after that it starts raining. During the winter night, if there are clouds in the sky, the heat released by the earth will get trapped between the earth and the clouds making the night warm. Clouds, wind, rain and humidity also plays a major role in changing the temperature of a day.
HOW IS MAXIMUM AND MINIMUM TEMPERATURE RECORDED?
Maximum and minimum temperature is recorded with the help of a Thermometer.
Name of the instrument is six’s thermometer named after the British scientist James six.
It is also called maximum and minimum thermometer.
Mounted within a wooden box, it is placed up side down. (vertically)
It consists of a cylindrical bulb and a spherical bulb at two ends of a “U” shaped tube.
The connecting lower part of the tube is filled with mercury.
The arms of both the tubes has a scale either in degree or a Fahrenheit scale.
Two small iron dumble shaped balls are placed within the tube touching the mercury.
Rest of the tube is filled with alcohol.
When the temperature of the surrounding surface increases, the alcohol expands and the mercury rises up.
Similarly, when the temperature decreases, the alcohol contracts and mercury pushes the ball upwards.
After reaching at the maximum and minimum temperatures, the indicators get fixed there.
Just like a clinical thermometer where mercury automatically does not fall down.
After recording the maximum and minimum temperatures, the indicators are set again with the help of a magnet.
This is how the maximum and minimum temperatures are recorded.
WHY DO WE RECORD THE MAXIMUM AND MINIMUM TEMPERATURES?
- It shows the difference between the maximum and the minimum temperature of a day.
- Helps in calculating the range of temperature.
- Also helps in predicting the earth’s climatic changes.
WHICH IS THE HOTTEST AND THE COLDEST PLACE ON EARTH?
Death valley in California (U.S.A.) holds the record for highest recorded air temperature (56.7 Degrees Celsius) in July 1913. This place is around 86 m below the sea level.The lowest ever temperatures has been recorded at Vostok station in Antarctica with (-89.2 Degrees Celsius) in July 1983.
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