On Thursday, May 16, 2013 1:11:13 PM UTC+1, MCC wrote:
Is there a good reason why isobars on a surface pressure chart are spaced

at 4 mb? I would have thought 5 mb spacing would have made more sense.

TIA

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MCC

It's an interesting question. When pressure was measured in inches, isobars were drawn at 0.2 inch intervals and I thought thee may be a correlation there but there isn't. Isobar intervals can be 2mb, 4mb or 8mb depending on the scale of the chart used so I suspect it's for that reason. ( hectoPascals (hPa)is the correct term these days!)