def compute_utm_zone(lon, lat):
    """
    Compute the UTM zone which contains
    the point with given longitude and latitude

    Args:
        lon (float): longitude of the point
        lat (float): latitude of the point

    Returns:
        str: UTM zone number + hemisphere (eg: '30N')
    """
    zone = int((lon + 180) // 6 + 1)
    hemisphere = 'N' if lat >= 0 else 'S'
    utm_zone = '{}{}'.format(zone, hemisphere)
    return utm_zone
