CALCULATIONS USING HYPSOMETRIC EQUATION

TERMINOLOGY AND DEFINITIONS

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SAMPLES USAGES OF "HypsoEq" CALCULATORS

 

Input
P1 =	pressure at height Z1
T (K) =	mean temperature bewteen Z2 and Z1
Z2-Z1 (m) =	difference in elevation between Z2 and Z1 (negative if Z1 is the higher elevation)
Calculate
P2 =	pressure at height Z2

For example, (P₁ , Z₁ )can be the sensor pressure reading and elevation, (P₂ , Z₂) can be the station pressure and station elevation.

 

Input
P1 (Pa) =	pressure at the bottom of the layer of atmosphere
P2(Pa) =	pressure at the top of the layer of the atmosphere
T (K) =	mean temperature bewteen Z2 and Z1
Calculate
Z2-Z1 (m) =	thickness of the layer of atmosphere

The height calculation in soundings in just the repeating process of thickness calculations for each layer of the atmosphere in the sounding.

Input
P2 =	station pressure
T (K) =	hypothetical temperature bewteen the station and the sea level  Typical choice is the 12-hour averge ambient temperature with standard lapse rate
Z2-Z1 (m) =	station elevation Z1 = 0 is the mean sea level positive above sea level and negative below sea level
Output
P1  =	mean sea level pressure

Note that the actual reported sea level pressure at each station would also take into account its unique local synoptic and climatological variation by using different representative lapse rate and other correction factor.  In U.S., tables are tabulated for each station in the calculation of sea level pressure.  In ASOS, the system calculates sea level pressure by using 12-hour average ambient temperature to access the proper pressure reduction ratio value, then calculates sea level pressure using
    SLP = P_s x R + C
    where
        P_s = station pressure
        R = pressure reduction ratio (depends on temperature and is unique to the elevation of that particular station)
        C = pressure reduction constant (most of the stations are set to 0, R is set to 1 if C is non-zero)
Detailed description can be found at  http://www.nwstc.noaa.gov/METEOR/d.ASM/SysMgr.HTML  and a brief survey and bibliography can be found at R. J. List (ed.), Smithsonian Meteorological Tables, 6th rev. ed., Washington, D. C., Smithsonian institution, pp. 203-5, 1951.

Report any errors in the calculators or send any suggestions to yoh@hurri.kean.edu 

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