def theta_fluc_from_theta_v_fluc(data, units, notation=None, return_full_df
    =True, inplace_units=True):
    """
    Derived from theta_v = theta(1 + 0.61 q)

    Parameters
    ----------
    data: pandas.dataframe
        dataframe with q, q', theta, theta_v'
    units: dict
        units dictionary
    notation: pymicra.Notation
        Notation object or None

    Returns
    -------
    float
        standard deviation of the thermodynamic temperature
    """
    import numpy as np
    from . import algs
    defs = algs.get_notation(notation)
    data = data.copy()
    if defs.mean_specific_humidity in data.columns:
        q_mean = data[defs.mean_specific_humidity]
    else:
        q_mean = data[defs.specific_humidity].mean()
    if defs.mean_thermodyn_temp in data.columns:
        theta_mean = data[defs.mean_thermodyn_temp]
    else:
        theta_mean = data[defs.thermodyn_temp].mean()
    theta_fluc = (data[defs.virtual_temperature_fluctuations] - 0.61 *
        theta_mean * data[defs.specific_humidity_fluctuations]) / (1.0 + 
        0.61 * q_mean)
    theta_fluc_unit = units[defs.virtual_temperature_fluctuations]
    if return_full_df:
        data.loc[:, (defs.thermodyn_temp_fluctuations)] = theta_fluc
        out = data
    else:
        theta_fluc.name = defs.thermodyn_temp_fluctuations
        out = theta_fluc
    if inplace_units:
        units.update({defs.thermodyn_temp_fluctuations: theta_fluc_unit})
    else:
        out = out, theta_fluc_unit
    return out
