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A visualization of global weather conditions, forecast by supercomputers
- moonlighter 13y agoAlso interesting: http://earth.nullschool.net/about.html http://earth.nullschool.net/about.html
- bradddd 13y agoThanks. As mesmerizing as the visual is, the explanation is useful.
- moonlighter 13y agoI'm always curious about the underlying modules used. Hadn't heard of when.js before: https://github.com/cujojs/when https://github.com/cujojs/when
- almosnow 13y agoHonest question. Why does weather behave different over oceans when compared to land?
- Keyframe 13y agoNo obstacles for wind, water vapor, temperature gradients of water..?
- thematt 13y agoProbably because wind speeds are faster over the ocean due to less friction. Mountains, trees, structures, etc. all affect that over land.
- acadien 13y agoAlso a larger heat exchange.
- aaren 13y agoThis. Even a little terrain is a lot more dynamically interesting than the ocean. There are also strong heat / surface moisture gradients on land (think edges of forests, cities, coasts), which play a big role in convection. By comparison, the ocean is an infinite plane so the dynamics are much more dependent on large scale forcings like the Earth's rotation and there is less local variability.
- Oculus 13y agoI'd wager a guess it's the water vapor.
- mturmon 13y agoGreat question. I think this is a data issue, not a weather issue. The data they are using over oceans comes from microwave scatterometers, which use radar to measure disturbances of the ocean surface caused by near-surface winds. Basically, the power of the radar return is affected by the interaction of the radar waves with the irregularities in the water surface (https://earth.esa.int/applications/data_util/SARDOCS/spaceborne/Radar_Courses/Radar_Course_III/bragg_scattering.htm https://earth.esa.int/applications/data_util/SARDOCS/spacebo...). To get a wind speed and direction from the radar power, you have to hit the surface from several different angles and perform an inversion. There are several ocean winds space missions that do this continuously from ~90-minute Earth orbits. For reference, one is QuikSCAT -- http://science.nasa.gov/missions/quikscat/ http://science.nasa.gov/missions/quikscat/ There is no analogous sensor that works over land. Hence, the data over land is not nearly as uniform, dense, and regularly observed. All that said, this particular visualization seems to have a calibration issue, because the land winds seem to be off in magnitude. I'm not enough of an expert to know if this is a problem with their data merging, sensor selection, stratification (e.g., winds at land surface may be lower than at sea surface, but up 50m they may be comparable), or something else. You can get other surprising things from remote sensing over oceans, including salinity, temperature, and incredibly precise elevation.
- aaren 13y agoCan you estimate the density of that data in space/time? Doesn't this vary with the overflights of the satellites? The land data is scarce in e.g. the Sahara, but the density over western Europe is pretty high. The land based data is continuous as well, and not affected by cloud cover.
- mturmon 13y agoI think it's a 50km spacing grid over the ocean. There are multiple satellites, so they get multiple scans per day. Also, they might ingest the data into a model, and report the model outputs, so this could enhance temporal resolution. Another issue with in situ sensors is calibration and uniformity. Unless they were installed by a central authority, they are likely to all be different. This makes analysis harder.
- mayhaffs 13y agoBeautiful design. This would be awesome to have hanging on a wall.
- kybernetyk 13y agoI considered having this displayed on a spare monitor I have but ultimately decided against it as the animation uses too much CPU for the rendering. Maybe I'll port it over to C++ if I find some time.
- Oculus 13y agoWicked cool visualization!
- LancerSykera 13y agoAt 10hPa, it's windy as dicks around the arctic circle. The antarctic, however, is relatively calm. Is that a seasonal thing? Will it be the opposite in June?
- michaelochurch 13y agoPolar-night jet stream: https://en.wikipedia.org/wiki/Jet_stream#Polar_night_jet https://en.wikipedia.org/wiki/Jet_stream#Polar_night_jet
- adolgert 13y agoThe javascript shows they are thinking about this as particle traces of wind velocities. In visualization, the technique is called Line Integral Convolution (LIC). Each line follows the direction of the wind vector, and the overall brightness is the sum of the magnitude of the winds under the line. This particular variant just uses the wind speed at one point under the line. LIC won't accidentally miss field singularities like vector-arrow representations, and there are variants that provide smooth animations. It's great that we've advanced from needing VTK to being able to do a visualization like this as a live movie, translating GRIB files to JSON.
- deleted 13y ago[deleted]
- mehwoot 13y agoIs this current weather conditions?
- arethuza 13y agoI checked it against the BBC Weather pressure map for the North Atlantic and Europe and the low and high pressures seem to match so it does look fairly "live".
- lucaspiller 13y agoIt says on the about page it is updated every three hours. http://earth.nullschool.net/about.html http://earth.nullschool.net/about.html EDIT: If you click on 'Earth' it brings up a menu with time controls.
- IvyMike 13y agoTime to whip out the hairy ball theorem: https://en.wikipedia.org/wiki/Hairy_ball_theorem https://en.wikipedia.org/wiki/Hairy_ball_theorem Yes I heard what I just said.
- siddboots 13y agoDoes the hairy ball theorem imply that there is always some place on the earth's surface where wind speed is zero?
- jackmaney 13y agoYes, assuming that the wind vectors are orthogonal to the Earth (and that the Earth is spherical). Also, by the Borsak-Ulam Theorem ( http://en.wikipedia.org/wiki/Borsuk%E2%80%93Ulam_theorem http://en.wikipedia.org/wiki/Borsuk%E2%80%93Ulam_theorem ), there are two points on the Earth directly opposite one another that have the same wind speed.
- nilkn 13y agoI think slight disturbances from being perfectly spherical are fine (since the Euler characteristic wouldn't be affected). The wind vectors not always being orthogonal to the Earth seems more damning, but maybe it is enough to just consider their projection onto the Earth's surface.
- 3rd3 13y agoIs it a problem that air can change in density/that it can be compressed?
- athst 13y agoThis is really cool, but it is clearly heavily influenced in design by Viegas and Wattenberg's Wind Map: http://hint.fm/wind/ http://hint.fm/wind/ The creator should really acknowledge their work...
- deleted 13y ago[deleted]
- navyrain 13y agoRelax; they credit it on the about page: http://earth.nullschool.net/about.html http://earth.nullschool.net/about.html
- cambecc 13y agoI have heavily acknowledged their work in tweets, on fb, on github, and in the about page. I have also thanked them directly. Also happy to note that most articles about the site also acknowledge the influence from hint.fm.
- seanalltogether 13y agoOut of programmer curiosity, is there a reason you have to stop rendering the globe while its moving?
- cambecc 13y agoThe NCEP data provides only 1º resolution, so bilinear interpolation is used to fill in the gaps. How much interpolation is needed depends on the zoom level and the projection. On top of that, the distortion caused by the projection must be applied to the interpolated wind field. All of these heavy calculations are done up front so the animation can be as fast as possible. So each time the orientation of the globe changes, we have to redo the calculations.
- ynniv 13y agoThis makes more sense in light of the view supporting zoom, which didn't occur to me the first time I visited the page. Perhaps add a note in the corner?
- Scaevolus 13y agoBeautiful! If you turn the globe upside down, the controls for rotating it are backwards. Some way to pan/zoom without pausing the visualization would be nice, but probably very difficult without moving to webgl-based rendering.
- nagarch 13y agoAmazing
- jheriko 13y agolooks broken here if i rotate it until it redraws which is a shame... i do find this interesting coming from a native rendering background. the idea of converting data from one, fairly inefficient format (FORTRAN friendly from the look) to a spectacularly less efficient format still is a bit mind boggling without appreciation for the web stack (JSON is not for run-time in my world - its for 'tools' or 'compile' time). the rendering is also quite underwhelming on a desktop PC - especially that it cuts out whilst rotating. there is some obvious stuff here that can be cached on inspection of the comments on github... for instance, since there is a lot of data processing already, how about 'unprojecting' the data to remove the extra interpolation overhead from having to apply a transform and its inverse? Just because they have chosen to project their data onto a sphere doesn't mean you have to follow suit... its probably a useful format for meteorologists or cartographers but its not suited for rendering at all. of course doing that will have similar results to a low pass filter unless you use a much higher density grid than the source (since you want a regular grid in your result and have irregular data points) - but visually that is very acceptable as a compromise. the obvious guess suggestion is webgl and a 3d canvas, and dropping any fancy svg or other elements if they need to be visually sycned up with precision and rendering all of it yourself in a single consistent way. in the browser world its often a bad idea to rely on the implementation of anything if you need guarantees of quality - there is a lot of variation and a lot of bugs that have persisted for years on end... i'd also suggest partitioning the data once its in 3d - a kd-tree or regular octree is quite easy to implement and understand and perfectly suited for this imo
- aaren 13y agoCan it display different data by playing with the url? e.g. I'm looking at http://earth.nullschool.net/#current/wind/isobaric/1000hPa/orthographic=-11.40,53.26,489 The only thing I can get to change is the lon, lat, zoom at the end. Are there more things I can change?