import math


def cart_2_lat_lon(cart):
    """
    Convert cartesian coordinates to lat/lon.

    Parameters
    ----------
    cart : tuple
        (x, y, z) cartesian coordinates on the unit sphere

    Returns
    -------
    lat : array-like
        latitude (-90 to 90)
    lon : array-like
        longitude (-180 to 180)
    """
    # calculations
    lon = math.atan2(cart[1], cart[0])
    lat = math.atan2(cart[2], math.sqrt(cart[0]**2 + cart[1]**2))
    # convert to degrees
    lat = math.degrees(lat)
    lon = math.degrees(lon)

    return lat, lon