Suntain

Living in Grenoble in the heart of French Alps, I always have been looking for sunrise and sunset information: not the one provided by all news or meteo websites, but really when the sun apperas over Belledonne, or disappears behind Chartreuse or Vercors mountains.

This information is crucial when planning a trail, or even more important if you are choosing the location of your house. In some areas in the Alps, you cannot see the sun during weeks in Winter: sun is always behind the mountain.

As I failed to find a free mobile application providing this information (only few costly web sites), I decided to develop my own: SUNTAIN, an application providing this information, based on your location. This Android Application has been developed with App Inventor from MIT. Terrain/mountain data are provide by EU Science Hub, and Time zone information by TimeZoneDB.

This application visualize position and trajectory of the sun, based on location and date. It provides:

  • Horizon (sea level) Sunrise and sunset time

  • Sunrise and sunset behind terrain/mountain: When sun appears and disappears!

Annual information is also available: sunrise and sunset along the year, daylight and sunshine duration for every day. On top of this, number of days with more (or less) than a specific amount of sunshine duration is available, plus much more information.

The application is available on Google Play in 5 different languages.

Documentation (V0.92)

Suntain main screen

  • Access to other screens

This button provides access to a second screen providing sunrise/sunset information along the year.

Help Information screen access

  • Map

This allows selection of the location where sunrise / sunset information is computed.

  • Pan the map by sliding your finger across the screen

  • Pinch-to-zoom: Touch with two fingers the map, and move them apart to zoom out, or together to zoom in

  • Tap with one finger to select a location and put the marker

  • Address

In this field enter the street address of the chosen location.

  • Sun path

Sun path diagram is displayed for the given location and date.

Sunrise & sunset hours are provided. These hours are either at horizon (sea level), or taking into account terrain information, depending on the selected mode (see below).

Sun position is displayed according to selected hour.

  • Control

Reset date to current one

Select local position using GPS position

Sun path mode.

  • Mountain: Sunrise and sunset taking into acount terrain/mountain

  • Horizon / seal level sunrise & sunset.

Sun position time

This button indicated the time zone. Touching this button update the time zone according to the selected location.

Date selection. This date is used to compute displayed sun path

Annual sunshine screen

This screen provides annual sunshine information: From January to December. Sea level as well as mountain aware sunrise and sunset are computed.

Daylight and sunshine duration during the year is provided.

Computing these data may take tens of seconds.

First pass is computing information at sea level.

Second pass computes data taking terrain information into account

Once computation is finished, annual information are displayed:

  • "Daylight": Sunrise and sunset at horizon (sea level)

  • "Sunshine": Sunrise & sunset behind terrain: when sun appears / disappears behind mountain

Mode selection is performed with these two buttons

This button triggers the display of daylight and sunshine duration along the year

Annual sushine hours and daylight hours are provided.

It is also possible to compute the number of days:

  • with more or less then a given number of sunny/daylight hours.

  • with sunset/sunrise before & after a given time.

Once, the number of hours have been entered, press:

Note: In some location: deep mountain valley, sun may not appear at all for few weeks / months. In such situation, sunshine duration is zero.

Exemple: If selected location (previous screen) is "Les Houches 74 France"

To compute the number of days when sun does not go higher than the surrounding mountains, set: "days with less than __ sunny hours to zero

About & Help screen

This screen provides Application information, a link to the online documentation (you are currently reading) and allows to select the language. Five different languages are available: English, French, Spanish, Italian and German.

Limitations

Current version: 0.92 has some limitations. Some of them are related to App Inventor, others to the implementation itself. If you find undocumented limitations or bug, please do not hesitate to report them to: jacques.dumarest@gmail.com

I you find this Application useful, please let me know, and if you have ideas for new features do not hesitate to propose them.

  • Android device must be connected to network or mobile data to allow the application to work: Terrain/mountain as well as time zone information are downloaded from a web server; if no network is available only "horizon" information is available.