Converting millibars to altitude?

Question

Hurricane Wilma set a record for the lowest air pressure ever measured in the Atlantic basin during a hurricane; 882 mb. How high would one have to ascend for the atmospheric pressure on a fair day to be 882 millibars?

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Answer 1

You can take the height as 1200 metres.Take the average surface pressure as 1013 mb and calculate the height using the relation 'one mb change for every 30 feet'(one metre=3.2808 feet).
Millibar change>1013 - 882=131.
corresponding height> 131 mltiplied by 30=3930 feet.
In metres>3930 divided by 3.2808=1198 metres.
This is only an approximation as temperature correction has also to be applied for getting the correct value using also the actual surface pressure at a paticular place.
The actual formula is Z=221T logp°/p where Z is height in feet, T is the average temperature(in absolute between the two levels) and p° is the surface pressure in mb and 'p' is the pressure in mb at the particular level.

Answer 2

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RE:
Converting millibars to altitude?
Hurricane Wilma set a record for the lowest air pressure ever measured in the Atlantic basin during a hurricane; 882 mb. How high would one have to ascend for the atmospheric pressure on a fair day to be 882 millibars?

Answer 3

About 4500ft. 850hPa is the standrad pressure level for 5000ft.

By the way, the unit used these days is hectoPascals, hPa, not millibars, mb. The figure is the same so barometers and altimeters don't need to be changed but the name of the unit is different. Millibars are in the centimetre/gram metric system. Pascals are in the standard metre/kilogram system

Answer 4

Just a few added notes. I don't really disagree with anything that was said.

The 882 mb reading actually is estimated. The dropsonde measured 884 from the aircraft that night. (Darn near fell out of my chair when that came in from the aircraft.) The final analysis concluded that the dropsonde was not in the center and that the pressure was likely two mb lower which I don't think anyone argues with.

The younger forecasters use the hPa units and really get on me when I still use mb which was used when I went to school. I like to point out to them to be totally correct they need to go by the SI (International System of Units) rules which would mean we should be using kiloPascals rather than hPa units since the internationally accepted sea level pressure would be above 1000 which is outside of the SI rules. Several countries are using kPa now (Canada for one).

Just a few little additional tip bits on the subject.

Too bad you can't split the points, the first two gents both deserve them.

Answer 5

The best way to convert millibars to height is to use the "Standard Atmosphere" which assumes a surface pressure of 1013.25 mb. In this atmosphere 577.52 mb is found at 4500 meters where the temperature is 6.4 F and the density of the air is .777 kg/cubic meter.

Answer 6

All the answers above are fantastic . it showes depth and . i just want to add that to my understanding 1 mb =33 feet .