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Name: Norvin
Status: other
Grade: other
Country: USA
Date: Winter 2012-2013


Question:
Super Typhoon Tip (1979): Erroneous Record? http://en.wikipedia.org/wiki/Typhoon_Tip I was doing some research and something dawned on me. Prior to 1982, 1 bar use to equal 101325 Pascals. Then in 1982, the International Union of Pure and Applied Chemistry lowered the value of the bar so it was equal to 100000 Pa making 1000 mb = 1000 hPa (hectopascals). And at mean sea level pressure, 1013.25 mb = 101325 Pa = 101.325 kPa = 1013.25 hPa so mb = hPa. I did a search for news articles on Google Books with a date range of 1979-1982:

https://www.google.com/search?q=Super+Typhoon+Tip&hl=en&safe=off&biw=1440&bih=756&sa=X&ei=cgIEUYu7C4mqkQWztYHYAg&ved=0CCQQpwUoBDgK&source=lnt&tbs=cdr%3A1%2Ccd_min%3A1979%2Ccd_max%3A1981&tbm=bks

I found a couple saying Super Typhoon Tip's record was 870 mb in that date range. So since it was recorded at that during the old mb value, would the record be even lower? Assuming my math is right: 870 / hPa = 101325 / 100000 101,325 hPa = 87,000,000 hPa = 858.6232420429312 So then Super Typhoon Tip's actual lowest pressure was lower than 870 mb/hPa then right? More like 859 mb/hPa?


Replies:
Norvin,

You appear to be confusing the unit "atmosphere" with the unit "bar".

One bar has always been equal to 100000 Pa (or 100 kPa, as we use).

Standard pressure at MSL = 1 atmosphere (not bar) = 1013.25 mb = 101.325 kPa = 101325 Pa

David R. Cook Meteorologist Atmospheric and Climate Research Program Environmental Science Division Argonne National Laboratory


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