def co2Stom(co2: float, params: dict) -> float:
    """
    CO2 concentration in the stomata

    Parameters
    ----------
    co2 : float
        Carbon dioxide concentration on air [μmol {CO2} mol-1 {air}]
    params : dict
        n_convCO2: float
            Conversion factor from the CO2-concentration of the greenhouse air

    Returns
    -------
    float
        CO2 concentration in the stomata [μmol {CO2} mol-1 {air}]

    """
    co2Stom = params['n_convCO2']*co2

    return co2Stom