This map is a project that I did this semester for a GIS class. It was an attempt to show density altitude visually.
Data was chosen to represent average values and standard variations. Average high and low monthly temperatures were used. Because humidity has a relatively small influence on determining density altitude, 68% humidity was used for all calculations. The standard pressure at sea level was adjusted for temperature for the high and low average monthly temperatures. The decrease in pressure altitude was determined for each airport using the altitude air pressure calculator at altitude.org which gave the pressure in millimeters of mercury (mm Hg). This was converted to inches of mercury (in Hg). The dew point for each high and low temperature was calculated using the dew point calculator at calculator.net. Finally, the air temperature, extrapolated average station pressure, and average dew point was entered into the NOAA Density Altitude Calculator and the figures were entered into the attribute table for the airport point layer using ArcMap software from Esri, Inc.
Actual airport elevation and average low and high temperature density altitude figures for Humboldt County Airports. Notice that the near-sea-level airports show negative density altitude numbers (below sea level) during cooler temperatures while inland airports show more than double the actual field elevation altitudes.