millibar• Consequently, for every 10 millibars more they fly about 80 metres higher.• I have heard that swallows follow their insectprey and these feel happiest at a barometric pressure of about 1010 millibars.• Earth has only 0. 3 millibars of carbondioxide and Mars an average of about 6 millibars.• The final pressure reduction is to about 50 millibars to supply the local network, which then takes gas to individualproperties.• Pressure had dropped to 29.5, one thousand millibars.