from input.natural_constants import *
import numpy as np

# ATMOSPHERE MODEL:


def T_air_simple(h):
    if 0 <= h <= 11000:
        res = 288.15 - 0.0065 * h
    elif 11000 < h <= 20000:
        res = 216.65
    elif h >= 20000:
        res = 216.65 + 0.0010 * (h - 20000)
    return res


def p_air_simple(h):
    if 0 <= h <= 11000:
        res = 101325 * ((288.15 - 0.0065 * h)/288.15) ** 5.25577
    elif 11000 < h <= 20000:
        res = 22632 * np.exp(-(h - 11000)/6341.62)
    elif h > 20000:
        res = 5474.87 * ((216.65 + 0.0010 * (h - 20000))/216.65) ** (-34.163)
    return res


def rho_air_simple(h):
    res = p_air(h)/(R_air * T_air(h))
    return res