Abe,
Regarding your question of February 2nd 2005 @ 11:23 a.m.
‘’The weatherman here sometimes says 41 D-Days, or 44 D-Days, or 45 D-Days, or 52 D-Days, or some other number. I thought there was only one D-Day, and that was June 6th 1944, when the United States, the Dominion of Canada, and the United Kingdom, landed in Europe.’’
Abe, there are nine D-Days.
Firstly, D-Day is just the one day of June 6th 1944.
Secondly a D-Day is 1° below 64° averaged over a 24 hr. period.
Thirdly a D-Day is 1° above 64° averaged over a 24 hr. period.
Fourthly a D-Day is 24° below 64° averaged over a 1 hr. period.
Fifthly a D-Day is 24° above 64° averaged over a 1 hr. period.
Sixthly a D-Day is 1° below 65° averaged over a 24 hr. period.
Seventhly a D-Day is 1° above 65° averaged over a 24 hr. period.
Eightly a D-Day is 24° below 65° averaged over a 1 hr. period.
Ninthly a D-Day is 24° above 65° averaged over a 1 hr. period.
In the United States a D-Day is calculated as follows:
0° - 96° temperature scale
32° lower reference point (water freezing point)
96° upper reference point (armpit temperature)
96° - 32° = 64°
64° -:- 2 = 32°
32° + 32° = 64°
PD-Day = average mean outside highest & lowest daily temperature is 64°
PD-Day = outside hourly temperature is 64°
HD-Day = average mean outside highest & lowest daily temperature is 1° below 64°
HD-Day = outside hourly temperature is 24° below 64°
CD-Day = average mean outside highest & lowest daily temperature is 1° above 64°
CD-Day = outside hourly temperature is 24° above 64°
PD-Day = Perfect Degree Day (do not heat & do not cool U.S. buildings)
HD-Day = Heating Degree Day (heat U.S. buildings)
CD-Day = Cooling Degree Day (cool U.S. buildings)
In Her Majesty’s Dominion of Canada a D-Day is calculated as follows:
0° - 96° temperature scale
32° lower reference point (water freezing point)
96° upper reference point (armpit temperature)
98.2° mouth temperature
98.2° - 32° = 66.2°
66.2° -:- 2 = 33.1°
32° + 33.1° = 65.1°
65.1° rounded to nearest whole number = 65°
PD-Day = average mean outside highest & lowest daily temperature is 65°
PD-Day = outside hourly temperature is 65°
HD-Day = average mean outside highest & lowest daily temperature is 1° below 65°
HD-Day = outside hourly temperature is 24° below 65°
CD-Day = average mean outside highest & lowest daily temperature is 1° above 65°
CD-Day = outside hourly temperature is 24° above 65°
PD-Day = Perfect Degree Day (do not heat & do not cool DoC buildings)
HD-Day = Heating Degree Day (heat DoC buildings)
CD-Day = Cooling Degree Day (cool DoC buildings)
Abe, the D-Day has been in general use since at least 1930. As you can probable guess, a D-Day is more a measurement of energy, than time. That is, one day can consist of zero D-Days, or 96 D-Days, or whatever the calculation, as it all depends on what the outside temperature is.
Always remember that folks have never agreed which one of the above two methods of calculation should be used exclusively. Although comparing the two calculations will show that the two different D-Days are often nearly the same, they are rarely exactly the same. So to be exact about the calculation, you will always have to contact the person, or organization concerned, and ask:
Is it the high & low method? (Average mean of only the highest temperature & lowest temperature of the day.)
Is it the integration method? (All temperatures taken every 1 hr., or 1/2 hr., or 1/3 hr., or 1/4 hr., or 1/5 hr., of 1/6 hr.)
Info @
http://www.weights-and-measures.com
And topic:
Common Temperature Scale
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