def pres2alt(pressure):
    """
    Determine altitude from site pressure.

    Parameters
    ----------
    pressure : numeric
        Atmospheric pressure (Pascals)

    Returns
    -------
    altitude : numeric
        Altitude in meters above sea level

    Notes
    ------
    The following assumptions are made

    ============================   ================
    Parameter                      Value
    ============================   ================
    Base pressure                  101325 Pa
    Temperature at zero altitude   288.15 K
    Gravitational acceleration     9.80665 m/s^2
    Lapse rate                     -6.5E-3 K/m
    Gas constant for air           287.053 J/(kgK)
    Relative Humidity              0%
    ============================   ================

    References
    -----------
    .. [1] "A Quick Derivation relating altitude to air pressure" from
       Portland State Aerospace Society, Version 1.03, 12/22/2004.
    """
    alt = 44331.5 - 4946.62 * pressure ** 0.190263
    return alt
