But when I lived in Yemen, the 40°F temperature swings from day to night rarely produced dew clinging to any structure as there was next to no moisture in the air to collect. They may have done something to encourage the water molecule to cling to the material. Could be a similar concept to the mentos/diet coke formation of CO2 gas bubbles.
If you are out at sea on a sailboat with no electricity (genuine purist) you might have rigged up a sheet of poly in that shape and got plenty of drinking water. It helps to be sitting over a large body of water. Probably wouldn’t be so effective in an arid inland region of dust and sand.