package grib

import "math"

var pressureLevels = []float64{1000, 975, 950, 925, 900, 875, 850, 825, 800, 775, 750, 725, 700, 650, 600, 550, 500, 450, 400, 350, 300, 250, 200, 150, 100, 70, 50, 30, 20, 10, 7, 5, 3, 2}

func pressureFromAlt(alt float64) float64 { // ICAO ISA
	return 1013.25 * math.Pow(1-alt/44307.69396, 5.255877)
}