Not only because of Wellington's notoriously bad weather reputation, we often found ourselves wondering how we can find the sunny areas for when the sun does come out. Even on a perfectly clear day, the capital's streets and public spaces are often shaded by the surrounding hills and high buildings. Particularly in winter, when the sun remains relatively low in the sky, knowing exactly when and where the sun will appear or disappear can be a very convenient piece of information. However this is much harder to calculate than the number of daylight hours between sunrise and sunset.
Where is the sunniest location? What is the latest spot to see the sun set? What time will the sun rise in my street? To answer questions like these, we developed an algorithm that allows rapid calculation of sunny and shaded areas that takes into account elevation data and the sun's relative position in the sky. Using publicly available data from the Wellington City Council, this method allows us to generate instant shade maps for the entire city at any given time.
Having generated direct sunlight data for the whole year, we can now derive some interesting statistics like the average daily exposure or the averages for morning and afternoon hours. These are presented for Wellington in the following interactive map.
