def abshumidity(T, equationSelect = 1):
    """ Atmopsheric absolute humidity [g/m3] for temperature in [K] between 248 K and 342 K.

    This function provides two similar equations, but with different constants.


    Args:
        | temperature (np.array[N,] or [N,1]):  in  [K].
        | equationSelect (int): select the equation to be used.


    Returns:
        | absolute humidity (np.array[N,] or [N,1]):  abs humidity in [g/m3]

    Raises:
        | No exception is raised.
    """

    #there are two options, the fist one seems more accurate (relative to test set)
    if equationSelect == 1:
        #http://www.vaisala.com/Vaisala%20Documents/Application%20notes/Humidity_Conversion_Formulas_B210973EN-D.pdf
        return ( 1325.2520998 * 10 **(7.5892*(T - 273.15)/(T -32.44)))/T

    else:
        #http://www.see.ed.ac.uk/~shs/Climate%20change/Data%20sources/Humidity%20with%20altidude.pdf
        return (1324.37872 * 2.718281828459046 **(17.67*(T - 273.16)/(T - 29.66)))/T