def METHOD_NAME(self) -> np.ndarray:
    """
    Calculate the updraught from CAPE data
    Calculation is 0.25 * sqrt(2 * cape)
    Returns zero where CAPE < 10 J kg-1
    """
    updraught = 0.25 * (2 * self.cape.data) ** 0.5
    updraught[self.cape.data < self._minimum_cape] = 0.0
    return updraught.astype(np.float32)