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30 degrees and snow is falling! How is that possible?

Question: Hi Teacher Joe! Recently I was watching a TV program that takes place in New York. Even though it was winter, they said it was 30 degrees outside. Another time, in spring, it was 75 degrees. My friend told me that westerners use a system for temperatures called "Fahrenheit" instead of centigrade. Could you tell me how Fahrenheit compares with centigrade and why western people use it? Thank you! ~ Andy, a university student in Yantai

Answer: Hi Andy. Thanks for your question. The Fahrenheit system of measuring temperature is part of the old English measuring system. Besides temperatures measured in Fahrenheit, we use yards, feet and inches instead of meters, centimeters and millimeters. We use miles instead of kilometers and quarts instead of liters. We use pounds and ounces instead of kilograms and grams. Although the metric system, including centigrade for temperatures, is now used around the world, old customs die hard in some places.

The metric system, based on a numerical base of 10, is much more logical and scientific than the English system. Actually, the old system is NOT used very much by westerners any more. The metric system has been implemented in almost every country in the world. In the 1960s, the United States also planned to change to the metric system. However, most individual states disagreed with the decision made in Washington and did not put it into practice. Some companies voluntarily show quantities using the metric system on their products, but few people think about it in their daily lives.

In any case, if you travel, study or work in the United States in the future, or if you're just watching a TV program and hear some strange numbers, you will need to know what they mean. The two key numbers in measuring temperature are the points where water freezes and where it boils. In centigrade, water boils at zero degrees and boils at 100 degrees. That's very neat! In Fahrenheit, by contrast, water freezes at 32 degrees and boils at 212 degrees! So, any temperature below 32 is "below freezing" in Fahrenheit. That's why it was 30 degrees in New York in winter.

If you want to convert precisely between Fahrenheit and centigrade, follow this formula: C*9/5 + 32 = F (Take the temperature in centigrade and multiply by nine. Then divide by five. Finally, add 32, and you've got the Fahrenheit temperature.) For example, what is the very pleasant 22 degrees centigrade in Fahrenheit? Let's see... 22 * 9 = 198. Dividing that by 5 gives us 40. Then 40 + 32 = 72. A very nice spring day!

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