SMF

Because lighter than air vehicles gain the most lift at the bottom of the atmosphere where pressure is greatest and can only ascend up to the altitude where air pressure just counterbalances the weight of the craft, I don't see any benefit to dropping a balloon into the atmosphere from the top. It would just expend a whole bunch more money to achieve the same altitude. SM

Insane_alien, thanks. That is nifty. SM

I understand the principle and was hoping for some more practical information. For example, running a gas burner into an envelope of hydrogen or helium would be adding hot CO2, so probably some sort of heat exchanger would be required. SM

Insane_alien. Do you know what the typical practical advantage is, what is the temperature of the gas, and how do they heat it? SM

A hot air balloon is approximately neutral at 100 degrees C and generates maximum lift at 120 C (250 F). This maximum temperature is constrained by the potential melting point of the envelope. I wonder what kind of performance might be gained from heated hydrogen or helium. I realize that there are some major practical considerations, at least for hydrogen, but where between hot air and vacuum would hot hydrogen or helium be, and how hot? SM

A few minutes ago walking on a path near my woodland home I found quite a handsome banana slug crawling across the path. I went and got a ruler and found that the slug was 182 mm long (a little more than 7 inches) and it was cooking along at an average of 162 mm/min (6.4 in/min). This translates to 9720 mm/hr (383 in/hr) or 0.00972 km/hr (0.006 mph). With an N of one and three timed distance measurements this should be considered a pilot study on banana slug speed. I don’t know why he/she was crossing the road or any other particulars. Banana slugs, presumably Ariolimax californicus in my area, are the largest slug in the Americas and while mine was in the average range, they can be much larger, but less than one foot. They are quite attractive with a yellow-green color, similar to a banana, but with large dark spots in different patterns on individuals. Check out the Banana Slug Derby race at Prairie Creek Redwoods State Park on the Northern California coast. Here is a story about the races- http://www.highlightskids.com/Science/Stories/SS0800_slugRace.asp SM

A species of tiger moth has been found to be able to jam the sonar of bats attempting to catch them.

Homing pigeons have a harder time getting home when their right nostril is blocked. This is a case of olfactory lateralization.

Is there a question here, or is this just some way to get me to spend some of my money?