fuckyeahfluiddynamics:

Today’s Mars is cold and dry, with a thin and insubstantial atmosphere. One of the challenges facing planetary scientists is unraveling the processes behind the complex terrain we can observe on the surface. Without flowing water, how do we explain these features? A new experiment suggests that the answer lies in boiling.

Surface conditions on Mars include atmospheric pressures low enough to be below the triple point of water* – the critical temperature and pressure where water vapor, liquid water, and ice can all exist simultaneously. This means that liquid water is unstable under Martian conditions; any water that seeped up to the surface would immediately begin to boil. That explosive boiling ejects sand particles, as seen in the animation above. The authors suggest that this hybrid process of wet percolation combined with vaporous ejection of sediment may better explain the Martian surface features we observe. (Image credit: M. Masse et al., source: Supplementary Movie 3; via Gizmodo; submitted by Paul vdB)

* The evidence we’ve seen so far on Mars points to briny water flowing near the surface. Although brines have lower freezing temperatures than pure water, the authors’ argument holds for them, as well. The boiling is simply not as vigorous.

(via fuckyeahfluiddynamics)

theeconomist:

Marai the cat is now a member of staff at the Serpukhov Museum of History and Art, Moscow Region, Russia. By popular demand, an application for a permanent post was submitted on his behalf to the museum’s managers. Marai negotiated a purrfect package of remuneration: he will receive fish and meat patties in lieu of a salary. Photo taken April 7th 2016. Credit: Getty Images/Vyacheslav Prokofyev

themathkid:

From “Proofs Without Words” by Roger Nelsen.

(via proofmathisbeautiful)

mapsbynik:

Full-size map

It’s the 2016 primary election season in the United States and this map represents a small part of it. It depicts the geographic distribution of votes for Hillary Clinton and Bernie Sanders in Travis County, Texas (home to Austin, the state’s capital city) during the Democratic Presidential Party on “Super Tuesday”, March 2.

The dots on the map represent voters. They were generated from the precinct-level election returns published by the Travis County Clerk’s office. Yellow dots represent votes for Sanders, while turquoise dots represent votes for Clinton. To give a sense of where groups of supporters live, the dots are constrained to cadastral parcels zoned for residential use. Dots are drawn randomly within each precinct and parcels; they do not represent the locations of individual voters.

Despite losing the state, Sanders won the county by about 4600 vote. Not a great surprise, given the county’s left-leaning reputation. Some general observations:

• Clinton actually won more precincts, 130 to 109.
• But those wins were of smaller magnitude compared to Sanders’. Clinton’s precincts were won by an average of 78 votes while Sanders averaged nearly double the margin with 142 votes per precinct.
• Geographically, Sanders showed extremely strong support in downtown neighborhoods, especially at UT–Austin and its surroundings. In the precinct housing most of the dorms, Sanders ran up a huge 5.5X, +1419 vote win. Impressive margins for Sanders were also found in the West University (+924), Pleasant Valley (+759) and Parker Lane (+622) neighborhoods.
• Clinton scored the most lopsided victory, 52 to 8 (6.5X margin), in Webberville in the southeast portion of the county.
• Clinton’s strongest areas of support came from the neighborhoods along RM 2222 west of Mopac, and on both sides of the river, scoring a handful of solid +200 to +300 vote victories. Additional strong showings were found at the Circle C Ranch developments in the southwest of the county and the Pecan Springs Springdale neighborhood in eastern Austin.

::

Election maps are always fun and I enjoyed putting this one together. The use of parcel data to limit the geographic extent of the symbology was a bit of an experiment for me. I think the results turned out well, revealing more detailed patterns among the candidate’s supporters than would have been revealed otherwise.

P.s. - For the curious: yes, I did look at the Republican Primary results as well. They weren’t that geographically interesting though, so I’m not likely to publish a map about it.

© Nik Freeman | mapsbynik.com 2016
Creative Commons Attribution-NonCommercial-ShareAlike
Election results from traviselectionresults.com
Precinct boundaries from the Travis County Tax Office
Parcel boundaries from Travis Central Appraisal District
Road lines from OpenStreetMap
County boundary from U.S. Census Bureau
Hand-crafted using Python, PostGIS and TileMill
Mercator Projection

(via mapsbynik)

mapsbynik:

Nobody lives here: The nearly 5 million Census Blocks with zero population

A Block is the smallest area unit used by the U.S. Census Bureau for tabulating statistics. As of the 2010 census, the United States consists of 11,078,300 Census Blocks. Of them, 4,871,270 blocks totaling 4.61 million square kilometers were reported to have no population living inside them. Despite having a population of more than 310 million people, 47 percent of the USA remains unoccupied.

Green shading indicates unoccupied Census Blocks. A single inhabitant is enough to omit a block from shading.

Update Jan 2015: Prints and canvas of the Nobody Live Here map are now available.

Update 2014.05.01: I’ve received a couple questions about Canada. Just to be clear, this map is of the United States only. It is based on 2010 data published by the U.S. Census Bureau, which for reasons I hope are apparent, does not include data on our friends in the Great White North. For a similar depiction of Canada, see this map whipped up by Michael Chung.

Map observations

The map tends to highlight two types of areas:

• places where human habitation is physically restrictive or impossible, and
• places where human habitation is prohibited by social or legal convention.

Water features such lakes, rivers, swamps and floodplains are revealed as places where it is hard for people to live. In addition, the mountains and deserts of the West, with their hostility to human survival, remain largely void of permanent population.

Of the places where settlement is prohibited, the most apparent are wilderness protection and recreational areas (such as national and state parks) and military bases. At the national and regional scales, these places appear as large green tracts surrounded by otherwise populated countryside.

At the local level, city and county parks emerge in contrast to their developed urban and suburban surroundings. At this scale, even major roads such as highways and interstates stretch like ribbons across the landscape.

Commercial and industrial areas are also likely to be green on this map. The local shopping mall, an office park, a warehouse district or a factory may have their own Census Blocks. But if people don’t live there, they will be considered “uninhabited”. So it should be noted that just because a block is unoccupied, that does not mean it is undeveloped.

Perhaps the two most notable anomalies on the map occur in Maine and the Dakotas. Northern Maine is conspicuously uninhabited. Despite being one of the earliest regions in North America to be settled by Europeans, the population there remains so low that large portions of the state’s interior have yet to be politically organized.

In the Dakotas, the border between North and South appears to be unexpectedly stark. Geographic phenomena typically do not respect artificial human boundaries. Throughout the rest of the map, state lines are often difficult to distinguish. But in the Dakotas, northern South Dakota is quite distinct from southern North Dakota. This is especially surprising considering that the county-level population density on both sides of the border is about the same at less than 10 people per square mile.

Update: On a more detailed examination of those two states, I’m convinced the contrast here is due to differences in the sizes of the blocks. North Dakota’s blocks are more consistently small (StDev of 3.3) while South Dakota’s are more varied in area (StDev of 9.28). West of the Missouri River, South Dakota’s blocks are substantially larger than those in ND, so a single inhabitant can appear to take up more space. Between the states, this provides a good lesson in how changing the size and shape of a geographic unit can alter perceptions of the landscape.

Finally, the differences between the eastern and western halves of the contiguous 48 states are particularly stark to me. In the east, with its larger population, unpopulated places are more likely to stand out on the map. In the west, the opposite is true. There, population centers stand out against the wilderness.

::

Ultimately, I made this map to show a different side of the United States. Human geographers spend so much time thinking about where people are. I thought I might bring some new insight by showing where they are not, adding contrast and context to the typical displays of the country’s population geography.

I’ve all but scratched the surface of insight available from examining this map. There’s a lot of data here. What trends and patterns do you see?

Errata

• Due to a cartographic mishap, the Gulf of California was missing from the original version. Though it was quickly fixed, that version keeps popping up across the Internet. It displeases me I see it, yet I’m amused that people keep reposting it without noticing the error. The geography gods judge those people harshly.
• Some islands may be missing on the hi-res edition if they were not a part of the waterbody data sets I used.

::

©mapsbynik 2014
Creative Commons Attribution-NonCommercial-ShareAlike
Block geography and population data from U.S. Census Bureau
Water body geography from National Hydrology Dataset and Natural Earth
Made with Tilemill
USGS National Atlas Equal Area Projection

(via mapsbynik)

letsgetprocessing:

Geometric Rain