4 ms·

> Lorenz realized that as moisture levels changed with the seasons, a collar of ice could form around the rock. With the rest of the lakebed covered in a thin,

> Lorenz realized that as moisture levels changed with the seasons, a collar of ice could form around the rock. With the rest of the lakebed covered in a thin, cold-but-not-frozen sheet of water, this ice collar would enable the rock it encased to float—slightly. So "ice collars" are responsible for moving 700 pound rocks on a "thin sheet of water"; and all this in the hottest and driest place in America? I must be missing something....

fragsworth 13y ago
It happens once every few years. Rain isn't as uncommon as yu think, and temperatures drop below 0 during winter frequently enough.
sethbannon 13y ago
During the winter months the temperature often drops below freezing: http://en.wikipedia.org/wiki/Death_Valley#Climate http://en.wikipedia.org/wiki/Death_Valley#Climate
jacques_chester 13y ago
Ice isn't actually that bad at supporting compressive loads. And, under pressure, it melts[0]. So if you put something heavy on top of an iceblock, it will be on a lubricated base. [0] A fun way to show this is "welding" ice cubes together by pushing them against each other.
- mistercow 13y ago
  One interesting point though is that current consensus is not that ice is slippery because it melts under pressure, but because of how air interferes with the bonding of the molecules at the surface.
diminoten 13y ago
Desert temperatures at night can get surprisingly low.
- kaybe 13y ago
  This is actually due to the low amount of water - very little of the greenhouse gas water vapour to keep the heat from radiating into space.
dredmorbius 13y ago
The Racetrack is a dry lake bed. Which is to say, it's a lake but the water level is (usually) below ground level. Often only just. Along some parts of the road running along the edge of The Racetrack is a trench and there's often water visible in this, 6-12" below the lakebed level. Moreover, the playa is at 3700 feet. The desert floor itself gets cold enough in the winter time, and the extra elevation only excacerbates this: adibiatic lapse accounts for about 3.5F cooling per 1000 feet, so Racetrack Playa would be 13F cooler than sea level. Deserts, despite their reputation as hot places (and yes, Death Valley and the Racetrack can be quite hot in the summer months) are largely characterized by their exposure. Which means they can get quite cold in wintertime.
- Turing_Machine 13y ago
  Many deserts can get quite cold at night, even in the summer time. No cloud cover, low humidity -> the heat just radiates off into space. The Romans supposedly used to make ice in the Middle East and North Africa by digging a deep pit and insulating it with straw. They'd open it up at night and cover it back up during the day.

fragsworth 13y ago

It happens once every few years. Rain isn't as uncommon as yu think, and temperatures drop below 0 during winter frequently enough.

sethbannon 13y ago

During the winter months the temperature often drops below freezing: http://en.wikipedia.org/wiki/Death_Valley#Climate http://en.wikipedia.org/wiki/Death_Valley#Climate

jacques_chester 13y ago

Ice isn't actually that bad at supporting compressive loads. And, under pressure, it melts[0]. So if you put something heavy on top of an iceblock, it will be on a lubricated base. [0] A fun way to show this is "welding" ice cubes together by pushing them against each other.

mistercow 13y ago
One interesting point though is that current consensus is not that ice is slippery because it melts under pressure, but because of how air interferes with the bonding of the molecules at the surface.

diminoten 13y ago

Desert temperatures at night can get surprisingly low.

kaybe 13y ago
This is actually due to the low amount of water - very little of the greenhouse gas water vapour to keep the heat from radiating into space.

dredmorbius 13y ago

The Racetrack is a dry lake bed. Which is to say, it's a lake but the water level is (usually) below ground level. Often only just. Along some parts of the road running along the edge of The Racetrack is a trench and there's often water visible in this, 6-12" below the lakebed level. Moreover, the playa is at 3700 feet. The desert floor itself gets cold enough in the winter time, and the extra elevation only excacerbates this: adibiatic lapse accounts for about 3.5F cooling per 1000 feet, so Racetrack Playa would be 13F cooler than sea level. Deserts, despite their reputation as hot places (and yes, Death Valley and the Racetrack can be quite hot in the summer months) are largely characterized by their exposure. Which means they can get quite cold in wintertime.

Turing_Machine 13y ago
Many deserts can get quite cold at night, even in the summer time. No cloud cover, low humidity -> the heat just radiates off into space. The Romans supposedly used to make ice in the Middle East and North Africa by digging a deep pit and insulating it with straw. They'd open it up at night and cover it back up during the day.