The sun and clouds forecast graph displays the expected number of sunlight hours for a specific location on a given day. The number of sunlight hours depends on cloud cover, the season, and the geographical location. Cloudiness is expressed as a percentage of the maximum cloud cover. It is often grouped into classes of 0-25%, 25-50%, etc. Lastly, the Ultraviolet (UV) Index is a standardized international measure of the strength of ultraviolet (UV) radiation from the sun at a particular location on a specific day. Figure 3.5A below illustrates how the sun and clouds forecast graph is presented on the platform.
Figure 3.5A – Sun and Clouds Forecast.
In the polar regions of the North, for instance, there can be up to 24 hours of sunlight during the summer months, depending on cloud cover, while at the same time, there might not be a single hour of sunlight in the southern polar regions.
The hours of sunlight are illustrated by golden bars that vary depending on the selected date. Figure 3.5B below shows how the sunlight hours forecasts are presented.
Figure 3.5B – Sunlight Hours Forecast Graph.
Cloud cover is illustrated below in Figure 3.5C and is represented by gray bars within the graph. Zero percent means that no clouds are visible in the sky. Fifty percent is equivalent to half of the sky being covered by clouds. One hundred percent cloud cover means that no clear sky is visible. If the cloud cover in multiple layers is fifty percent, only a small portion of the sky will be visible
Figure 3.5C – Cloud Cover Forecast Graph.
Finally, below the sun and clouds forecast graph, there is the representation of the Ultraviolet (UV) Index, which is a standardized international measure of the strength of ultraviolet (UV) radiation from the sun at a specific location on a given day. Figure 3.5D illustrates how the UV Index is represented.
Figure 3.5D – Ultraviolet Index Representation.
The purpose of the UV Index is to help people effectively protect themselves from UV rays, which, when exposure is excessive, can cause sunburn, eye damage such as cataracts, skin aging, and skin cancer.
Public health organizations recommend that people protect themselves (e.g., by applying sunscreen to the skin and wearing a hat) when the UV Index is 3 or higher.
If the user opts to view the detailed “hour-by-hour” forecast, they should click on the “View Hourly” button at the bottom of the screen, as illustrated in Figure 3.5E below.
Figure 3.5E – “View Hourly” Sun and Clouds Forecast Button.
Clicking on the “View Hourly” button will open the screen illustrated in Figure 3.5F, where different forecast dates for sun and clouds are available at the top of the screen, with their respective hours shown at the bottom.
Figure 3.5F – Hour-by-Hour Sun and Clouds Forecast Screen.