November 27, 2009

Happy Birthday, Anders Celsius

Born on this date in 1701, Celsius was a Swedish astronomer who ended up immortalized because of the temperature scale he proposed. He made great efforts to very accurately measure the temperature of freezing water and of boiling water. He called the temperature at which water freezes 100, and the temperature at which it boils 0, and he then divided this amount into 100 small, equal steps (or “centigrade,” which is what he called his scale). He presented his scale to other scientists; for years, his thermometer was called the Swedish thermometer, although some used Celsius's term, centigrade. Now, of course, this scale is used worldwide in science and in many countries for all temperature measurements—and it is named after Celsius.


Did you catch what I said in the first paragraph?-- Celsius's system went from a low of 100 to a high of 0 !!!—so, when the temperature got hotter, it was going down! This was so counter-intuitive that, almost as soon as Celsius died at age 43, scientists reversed his scale. Now 0 degrees Celsius is the temperature at which water freezes, and 100 degrees Celsius is the boiling point.

Ahhh...much better!

(Of course, temperatures do get colder than 0 degrees C. (we use negative numbers for these measurements), and temperatures do get hotter than 100 degrees C., too.)

• Here is a simple algorithm to convert Fahrenheit to Celsius or vice versa:

First, whether your original temperature is Celsius or Fahrenheit, add 40.

Second, if you started with Fahrenheit, multiply by .55555 (a decimal point followed by 5 fives). If you started with Celsius, multiply by 1.8.

Third, subtract 40.

EXAMPLE:

(1) Start with 32 degrees F. Add 40. You will get 72.
(2) Multiply by .55555. You will get 39.9996. Round up to 40.
(3) Subtract 40. You get 0 degrees C. – which is correct.

THINGS TO DO:

A Celsius/Fahrenheit converter can be found here.

Activities and games about weather can be found here.