@classmethod<EOL><INDENT>def from_ashrae_clear_sky(cls, location, sky_clearness=<NUM_LIT:1>, timestep=<NUM_LIT:1>,<EOL>is_leap_year=False):<DEDENT>
<EOL>metadata = {'<STR_LIT:source>': location.source, '<STR_LIT>': location.country,<EOL>'<STR_LIT>': location.city}<EOL>sp = Sunpath.from_location(location)<EOL>sp.is_leap_year = is_leap_year<EOL>altitudes = [[] for i in range(<NUM_LIT:12>)]<EOL>dates = cls._get_datetimes(timestep, is_leap_year)<EOL>for t_date in dates:<EOL><INDENT>sun = sp.calculate_sun_from_date_time(t_date)<EOL>altitudes[sun.datetime.month - <NUM_LIT:1>].append(sun.altitude)<EOL><DEDENT>direct_norm, diffuse_horiz = [], []<EOL>for i_mon, alt_list in enumerate(altitudes):<EOL><INDENT>dir_norm_rad, dif_horiz_rad = ashrae_clear_sky(<EOL>alt_list, i_mon + <NUM_LIT:1>, sky_clearness)<EOL>direct_norm.extend(dir_norm_rad)<EOL>diffuse_horiz.extend(dif_horiz_rad)<EOL><DEDENT>direct_norm_rad, diffuse_horiz_rad =cls._get_data_collections(direct_norm, diffuse_horiz,<EOL>metadata, timestep, is_leap_year)<EOL>return cls(location, direct_norm_rad, diffuse_horiz_rad, timestep, is_leap_year)<EOL>
Create a wea object representing an original ASHRAE Clear Sky.

        The original ASHRAE Clear Sky is intended to determine peak solar load
        and sizing parmeters for HVAC systems.  It is not the sky model
        currently recommended by ASHRAE since it usually overestimates the
        amount of solar irradiance in comparison to the newer ASHRAE Revised
        Clear Sky ("Tau Model"). However, the original model here is still
        useful for cases where monthly optical depth values are not known. For
        more information on the ASHRAE Clear Sky model, see the EnergyPlus
        Engineering Reference:
        https://bigladdersoftware.com/epx/docs/8-9/engineering-reference/climate-calculations.html

        Args:
            location: Ladybug location object.
            sky_clearness: A factor that will be multiplied by the output of
                the model. This is to help account for locations where clear,
                dry skies predominate (e.g., at high elevations) or,
                conversely, where hazy and humid conditions are frequent. See
                Threlkeld and Jordan (1958) for recommended values. Typical
                values range from 0.95 to 1.05 and are usually never more
                than 1.2. Default is set to 1.0.
            timestep: An optional integer to set the number of time steps per
                hour. Default is 1 for one value per hour.
            is_leap_year: A boolean to indicate if values are representing a leap year.
                Default is False.