import math


def get_delta(temp):
    """
    Reference page number: 28-29
    Parameters
    ------------------------------
    temp: (``float``)
        The air temperature in degrees Celcius
    Returns
    ------------------------------
    delta: (``float``)
        The slope of the saturation vapor pressure-temperature curve in kPa/C
    """
    numerator = 2503 * math.exp((17.27 * temp) / (temp + 237.3))
    denominator = math.pow(temp + 237.3, 2)
    delta = numerator / denominator
    return delta