Wikipedia:Reference desk/Archives/Science/2023 May 19

= May 19 =

Moss growth and ant hills
I find the traditional explanation for moss growth on the northern part of trees somewhat puzzling. Is the air and bark temperature difference between a northern and all other parts of a tree that big? I suspect it to be within fractions of a Celsius degree at most, if not identical which doesn't seem to be enough to make a difference. Same for humidity. The distance difference in such cases is typically between several to several tens of centimeters.

A similar explanation for ant hills on the southern side also puzzles me. If the sun rises at the east, setting at the west, it would be the eastern side that receives most sunlight, being effectively more warmer rather than southern side. A southern side appears to be roughly perpendicular to most sunrays and thus less insolated than the eastern side. Thanks. 212.180.235.46 (talk) 21:12, 19 May 2023 (UTC)


 * May I suggest you do a little experimentwhen the sun is shining.Try going behind a tree hidden from the sun, and then in front of the tree in the snlight and see how difficult it is or not to detect this fraction of a degree you talk about. Ants favor the south east a bit more because they need to warm up in the morning and don't need the heat so much later. NadVolum (talk) 21:55, 19 May 2023 (UTC)


 * The Moss article explains why moss likes north sides of trees and shady, moister areas. As for sun angles otherwise, I can tell you from working in glass buildings (which are sort of like corporate anthills) that the sides facing the western sun tend to get hotter during the day, while the sides facing the eastern sun slowly level out as the day goes on. ←Baseball Bugs What's up, Doc? carrots→ 22:53, 19 May 2023 (UTC)


 * At the risk of stating the bleeding obvious, the sun never shines from the north (in the northern hemisphere that is). Alansplodge (talk) 10:44, 20 May 2023 (UTC)
 * @Alansplodge: axial_tilt_vs_tropical_and_polar_circles.svg Pedantically, that's ''the sun never shines from the north (north of the Tropic of Cancer that is). Bazza (talk) 11:06, 20 May 2023 (UTC)
 * Quite right, I stand corrected; although I suspect that moss growing on the northern side of trees is not an observable phenomenon in the tropics. Alansplodge (talk) 11:14, 20 May 2023 (UTC)