Your Observation and Report
You continue with your weather observations onboard the Kearsarge and record the pressure measurements. You view the barometer, located 50 feet above sea level, and read a pressure of 29.091 inches Hg.
Here is the Additive Reduction Constants table for your use if you need.
What pressure observations do you record on your observing form? Type your answers in the boxes, then click Done.
The station pressure is encoded in inches Hg to the nearest thousandth, 29.091. The sea level pressure is computed by adding the appropriate additive reduction constant to station pressure. In this case, 29.091 + 0.053 = 29.14 Hg. Because 1 in Hg = 33.864 hPa, we can multiply 29.14 in Hg x 33.864 hPa/in Hg to get a sea level pressure of 986.8 hPa. It is encoded as 868. The altimeter setting is encoded in inches Hg to the nearest hundredth, 2914.