Ken Sterling Ken Sterling wrote:

I would fathom a guess that hot water is "lighter" than cold water,

At temp T (F), it weighs about 62.46-0.01(T-68) lb/ft^3.

therefore if you had a 100' of hose, and one end of it is in 25' of
direct sunlite (and had been for a period of time) about 20 degrees hotter,
the colder water would push the hot water a little higher in the tube...

Imagine filling a 110 foot x 1 ft^2 hose filled with 100' of 68 F water.
The water weighs 100x62.46 = 6246 pounds. Now heat half of the water (3123
pounds of it) to 88 F. A cubic foot of the warmer water weighs about 62.26
pounds, so the warmer water now occupies 3123/62.26 = 50.1606 feet of hose,
ie the hose now contains 100.1606 feet of water.

Imagine hanging one end from the shady side of a 50 foot tall building at
68 F and hanging the other end from the sunny side around a corner. We might
see water column heights Hc and Hw, where Hc + Hw = 100.1606 feet, and
62.46Hc = 62.26Hw, which makes Hc = 0.9968Hw, so 1.9968Hw = 100.1606, and
Hw = 50.1606', and Hc = 50', and Hw - Hc = 0.1606 feet, or 1.927 inches.

If all the hose were on level ground, we wouldn't see any height difference,
although both heights would rise by 0.9636 inches, or more, if air bubbles
undissolved from the warmer water.

Nick