The Sun and Clouds tab presents an overview of various climatic factors that relate to sun, solar position, intensity, and cloud cover, in particular:

• Apparent sunpath for the location (spherical and cartesian projection)

• Global and Diffuse Horizontal Solar Radiation

• Cloud coverage

• Customizable daily and hourly maps

Apparent sun path for the location

Clima allows the user to visualize the sun path for the chosen location in spherical and cartesian projection

Clima optionally allows a variety of variables to be overlayed on either sun path type.

This allows the user to identify climatic patterns in relation to the apparent solar position. Data are plotted on the analemma.

Video Tutorial

Learn more about the Sun and Cloud tab by watching the following video.

In the cartesian coordinates, the solar elevation is plotted on the y-axis and the azimuth is plotted on the x-axis. It shows the path we would see the sun follow if we took a video with the camera in the right direction of the horizon (as notable comparing the following two figures).

A photographic paper left inside a cider exposed through a pinhole aperture captured 8 years of sun full cycles. The photographic paper immortalized a real cartesian sun path.

The cartesian sun path is comprised of various graphical elements overlayed on one another.

We'll attempt to describe them individually below.

The cartesian sun path can be read as a projection of the spherical sun path diagram. The map projection encompasses a wide range of transformations used to represent the curved two-dimensional surface of a globe on a plane. The cylindrical projection is obtained by unraveling the globe inside a cylinder. Among the different distortion versions of the globe in a flat map, the Miller Projection is a compromise that does not sacrifice either area or map shapes excessively at the extremes.

The planes parallel to the x-axis can be understood as sections of the imaginary sky dome. Each plane represents an increment of 10 degrees from the horizon. Thereby, it is possible to read the height of the sun in each of its positions.

The geographical coordinates are plotted on the x-axis in degrees, going from left to right: North (0°), East (90°), south (180°), and West (270°).

The upper spline represents the sun's path during the summer solstice, i.e. the maximum height of the sun above the horizon for the examined location. Meanwhile, the lower spline is the sun’s path during the winter solstice, when the sun reaches the lowest height above the horizon. The spline in the middle is the sun's path during the Equinoxes.

Clima displays hourly Global and Diffuse Horizontal Solar Radiation values for a typical day for each month.

Typical daily graphs showing the amount of energy gained from the sun have many uses, such as:

• design the building with a passive approach, to control solar gains and reduce energy consumption (allow solar gain during months of heating demand and block them during periods of cooling demand, see for reference the degree days);

• manage the direct solar gain through the glass, to evaluate solar shading devices (most useful in locations with high temperatures and a strong direct component);

• manage the indirect solar gain transfer into the building with a time shift, exploiting the thermal mass, heating thick walls or concrete floors, or designing special rooms adjacent to the main spaces that rely on convection to transfer the heat, such as sunroom or Trombe wall;

• evaluating sustainable renewable energy solutions such as solar thermal or photovoltaic panels.

The integral of the curves in the graphs is the total energy (in Wh/m²), supplied by the sun. Be careful in considering the different types of solar radiation.

The cloud coverage diagram reports, for every month of the year the frequency of "clear", "cloudy" or "intermediate" conditions.

As the Cloud cover is reported in tenths of coverage (i.e. 0 is 0/10 covered. 10 is total coverage) for the purpose of this graph we have simplified the scale as per the table below.

• Global Horizontal Irradiance (GHI) is the total irradiance from the sun on a horizontal surface. It is the sum of the Diffuse Horizontal Irradiance and the Direct Normal Irradiance, projected onto the horizontal plane using the solar zenith angle (z).

• Diffuse Horizontal Irradiance (DHI) is the radiation that arrives from the entirety of the sky dome, except the solar disc. Is the radiation that has been scattered by molecules and particles in the atmosphere. It is measured on a horizontal surface

• Direct Normal Irradiance (DNI) is the measurement of the intensity of sunlight on a surface perpendicular (normal) to the sun, as such, in very clear sky conditions and low solar altitudes, the Direct Normal Irradiance can be higher than the Global Horizontal Irradiance.

Clima allows the user to visualize daily charts and heatmaps of all the variables listed in 'Apparent sun path for the location'.

The chart above shows the scatter plot of all hourly data on all days of the month and the typical monthly trend.

Heat maps allow the intensity of values to be perceived through color palettes. These graphs are very helpful in seeing how magnitudes vary throughout the year.

The spherical sun path is comprised of various graphical elements overlayed on one another.

We'll attempt to describe them individually below.

The sunpath can be read as a compass, with the radial lines indicating the different directions.

The concentric circles can be understood as sections of the immaginary sky dome. Each ring represents an increment of 10 degreees from the horizon. As such, they help visualize the solar altitude for each sun position.

The daily path of the sun on a given day can be traced by following a sun path spline from the east (sunrise) to the west (sunset).

The upper spline represents the sun's path during the summer solstice, i.e. the maximum height of the sun above the horizon for the examined location. Meanwhile, the lower spline is the sun’s path during the winter solstice, when the sun reaches the lowest height above the horizon. The spline in the middle is the sun's path during the Equinoxes.

Gathering the sun's positions for each time of day, during all days of the year, creates splines called Analemmas.

Overlapping photos taken at the same time of day over the course of an entire year results in an analemma like the one in the picture.