def condTo25(cond, temp):
    """
    Converts given value of specific conductance to the value at 25 C.

    Uses the relation from Sorensen and Glass (1987), as found in
    Equation 4 of Hayashi (2004).

    Parameters
    ----------
    cond : float or array
       measured value of specific conductance
    temp : float or array
       temperature of water at which specific conductance was measured.
   
    Returns
    -------
    cond25: float or array
       specific conductance at 25 C.

    """
    a = 0.0187 #from Hayashi, 2004
    cond25 = cond/(1+a*(temp - 25.0))
    return cond25