3 ms·

It would be interesting to put these out at night and have them drop a designated area below the dew point and collect water. As I understand it, nighttime tem

It would be interesting to put these out at night and have them drop a designated area below the dew point and collect water. As I understand it, nighttime temps get near the dew point but often don’t hit it because water in the air releases so much heat.

deepsun 3y ago
Mold/algae will grow on the wet surfaces in a matter of days, destroying the main promise of the material.
- hamandcheese 3y ago
  Im not so sure. Mildew has to eat something. Assuming the surface is kept clean and water is collected regularly, it shouldn't be a major problem. You don't see mildew growing on cars very often, do you? Yet, growing up in Florida, I'd see few covered cars in the morning all the time.
  - deepsun 3y ago
    Cars not, they go to wash. Those who don't are indeed visibly dusty/moldy. Wet roofs and other surfaces -- pretty much all the time, especially in humid climates (like Hong Kong, where the research is made). Same for glass windows (we have window-washer job for that reason). Surfaces can be cleaned with pressure washer, but unlike purely aesthetical reasons, I'm saying that the main feature of this material may stop working in a matter of days due to even minuscule amount of growth.
j-a-a-p 3y ago
At night they would do the opposite what you suggest. A very white surface would stay warmer, a black (in the sense of IR black) surface would radiate heat better and cool below dew.
- pertymcpert 3y ago
  Wouldn't a black surface be absorbing heat from above it?
  - j-a-a-p 3y ago
    The question then is, what heat? From the stars and moon is almost nothing. No idea what it exactly is, but assume that a clear sky at night has about -170 C temp (you are looking at the cold universe, only some CO2 in between to absorb). So the net radiation is always outbound. And the best way to radiate are black (not the color but as in the definition of heat radiation) objects.
    - pertymcpert 3y ago
      The question I was really asking was answered by this: https://physics.stackexchange.com/questions/159856/why-is-black-the-best-emitter https://physics.stackexchange.com/questions/159856/why-is-bl... I.e. surfaces which are good at absorbing radiation are also good at emitting, which I didn't know.

deepsun 3y ago

Mold/algae will grow on the wet surfaces in a matter of days, destroying the main promise of the material.

hamandcheese 3y ago
Im not so sure. Mildew has to eat something. Assuming the surface is kept clean and water is collected regularly, it shouldn't be a major problem. You don't see mildew growing on cars very often, do you? Yet, growing up in Florida, I'd see few covered cars in the morning all the time.
- deepsun 3y ago
  Cars not, they go to wash. Those who don't are indeed visibly dusty/moldy. Wet roofs and other surfaces -- pretty much all the time, especially in humid climates (like Hong Kong, where the research is made). Same for glass windows (we have window-washer job for that reason). Surfaces can be cleaned with pressure washer, but unlike purely aesthetical reasons, I'm saying that the main feature of this material may stop working in a matter of days due to even minuscule amount of growth.

j-a-a-p 3y ago

At night they would do the opposite what you suggest. A very white surface would stay warmer, a black (in the sense of IR black) surface would radiate heat better and cool below dew.

pertymcpert 3y ago
Wouldn't a black surface be absorbing heat from above it?
- j-a-a-p 3y ago
  The question then is, what heat? From the stars and moon is almost nothing. No idea what it exactly is, but assume that a clear sky at night has about -170 C temp (you are looking at the cold universe, only some CO2 in between to absorb). So the net radiation is always outbound. And the best way to radiate are black (not the color but as in the definition of heat radiation) objects.
  - pertymcpert 3y ago
    The question I was really asking was answered by this: https://physics.stackexchange.com/questions/159856/why-is-black-the-best-emitter https://physics.stackexchange.com/questions/159856/why-is-bl... I.e. surfaces which are good at absorbing radiation are also good at emitting, which I didn't know.