WeaktherKit REST API returns snowfallAmount.
DarkSky used to return precipAccumulation (for snow.)
Are these measuring the same thing? The Weatherkit Docs say that snowfallAmount represents: "The depth of snow as ice crystals forecasted to occur during the day, in millimeters."
I'm not sure I really understand. Where is the "depth" to "occur"? Is it supposed to refer to the actual amount of snow predicted to accumulate (like, on the ground)?
(The documentation for transitioning from DarkSky https://developer.apple.com/weatherkit/get-started/ doesn't really clarify, I don't think.)
snowfallAmount gives the amount of precipitation that falls as snow measured as the depth of snow crystals with no melting, as opposed to precipitationAmount which is the amount of precipitation measured as depth of water after melting. The difference is usually around a factor of 10.
Snow is mostly empty space, and how much empty space is in the snow--how "fluffy" it is--is partially a function of temperature. The snowfallAmount gives depth of snow if it were to fall on the ground with no melting, no change in its temperature, and no compression as layers of snow accumulate. precipitationAmount gives the depth water you would have if you let all the precipitation fall and then melted it with no evaporation.
snowfallAmount may be greater than the observed snow accumulation since snow that falls on warm ground will melt rather than accumulate.
