# BarometricFormula: Shows FUNCTION, AXIS, LINE, ALARM

### Air pressure as a FUNCTION of height over sea level and temperature. AXIS plots (h,p) axes. LINE plots pressure vs height for different temperatures..

• Estimate how air pressure depends on height over sea level and on temperature
• FUNCTION pressure(meter, centigrade) returns air pressure in hectopascal
• AXIS initializes a pressure-height graph
• LINE plots pressure vs height for 5 (blue) and 30 (red) degrees centigrade
• ALARM waits for a user interaction to keep the graph drawn on the script window
• ! no declarations needed for numeric variables
•  pressure(800, 15) ! gas pressure at 800m and 15C in hPa or mbar 920.779
•  mbarPerMeter = pressure(800,15) - pressure(801,15) ! nice to remember 0.11115
•  mbarPerDegree = pressure(800,16) - pressure(800,15) ! amazing, isn't it? 0.307579
• AXIS(MiN=0, MaX=1000, Y, MiN=890, Max=1013, Title="height", Y, Title="pressure")
• LINE(X=h, Y=pressure(h, 5), Color=9, Points=100)
• LINE(X=h, Y=pressure(h,30), Color=12, Points=100) ! ⇾ colors
• ALARM(1) ! wait for keyboard or mouse activity ! how to delay wait quit
• END ! terminate this "main" program
• FUNCTION pressure(meters, centigrade) ! in hectopascal hPa or mbar or mb how to define a function procedure
• pressure = 1013.25*(1 - 0.0065 * meters/(centigrade + 273.15))^5.255
• END ! terminate this function (required)

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