Tanvi Misra is a staff writer for CityLab covering immigrant communities, housing, economic inequality, and culture. She also authors Navigator, a weekly newsletter for urban explorers (subscribe here). Her work also appears in The Atlantic, NPR, and BBC.
An interactive data viz tracks how many rays Wellington actually receives.
Wellington, the capital city of New Zealand, gets more than 2,000 hours of sunshine each year. It's no Los Angeles, which receives more than 3,000 hours, but that's a substantial amount of sun. Still, Wellington doesn't have the sunniest reputation. A recent blog post in the New Zealand Herald calls the city's weather "notoriously bad":
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.
That post was written by developers Laurent Lebreton and Timo Franz of Dumpark, a data visualization group. The agency has created an interactive map that shows how much daily sunlight the New Zealand capital actually receives. Users can zoom in and out of different parts of the city, and also see changes in sunlight at different times of the day.
The developers first calculated hours of direct sunlight at every point in the city. Their algorithm takes into account not just the position of the sun relative to the earth at a given time of day, but also the effect of local terrain and buildings on sunshine. Using this approach, they animated the path of shade cast on city's surfaces over time.
The animated gifs below show how light washes over the city on Winter Solstice (June 21) and Summer Solstice (December 21). (Remember, New Zealand is in the Southern Hemisphere so summer and winter seasons are sort-of reversed.)
The interactive map is the result of Lebreton, Franz, and colleagues crunching publicly available sunlight data for a whole year. It shows the average daily sunlight (lead image above), morning sun exposure (below, top), and afternoon sun exposure (below, bottom). The areas receiving the largest amount of direct sunlight on average are whiter, and the ones that receive fewer hours are darker:
The developers explain some of the map's revelations:
The data clearly shows how very little sun the business district streets receive in a day and highlight which buildings and residential neighborhoods receives the largest amount of sunlight.
They also explain how they can use the data to compare how much sunlight one street gets relative to another, and show the impact of street width and building height. Here's Cuba Street and Manners Street:
The high buildings lining lower Cuba Street tend to restrict the light it gets in summer and winter:
On the other hand, Manners Street is narrower than Courtenay Place, so the latter tends to receive more sunlight, on average:
The map isn't just for those who want to know whether or not they'll need sunglasses. It can be useful for people working in real estate, road safety, solar energy, agriculture, and hospitality, the developers write. For now, only Wellington is on the map. But the developers are planning to add more cities to the list, so it might be your city's turn next to bask in the sun.