I just moved to the mission district in San Francisco. On my street there are numerous unremarkable trees (not sure what type, can post photos if it’s helpful). For reasons that are entirely beyond my comprehension I have noticed a light mist when I walk under the trees. This has always been when there is a warm blue sky with not s drop of rain anywhere else. I even noticed a few drops on my iPhone screen so it’s not just a sensation (though it is very light). I looked carefully and the trees are sufficiently far from any house or building so they must be the source of the moisture.
What phenomenon would cause this lift mist to fall from trees in SF?
Could be scale infestation. When that happens, the insects (scale) secrete a watery substance called honeydew, which often lightly drips off of the leaves.
I can’t see it on the video, but I dont disbelieve you. It is probably aphids or other insects - tree sap is very poor in protein, so they havevto drink and excrete a lot of it in order to get the nutriment they need.
Catch a drop and taste it. If it’s sweet, it’s probably aphid piss.
I can’t watch the video, but living in the Mission, my best guess would be fog drip. With the enormous amount of fog that we’ve been getting this summer, any tree that retains and coalesces moisture from the fog is likely to be dripping all day long. I know I’m constantly being misted on as I walk around the Mission, even after the fog has (temporarily) lifted.
IIRC, many trees can excrete moisture under the right conditions which is a self cooling defense mechanism. Hot & still air are required. As I have observed this from trees on different properties in Oklahoma & Texas, it is not just one type of tree I don’t think but is is not connected to recent rain or levels of humidity which are recent enough have lingering moisture. As for bugs, I did not note any over the years and it would also not seem reasonable to be tied to the same conditions as the tree rain IMO.
Maybe the information was never published anywhere and it may be a false memory but for 63 of my 71 years I have been noticing this phenomenon…
The mimosa trees in my yard often mist or drip lightly when it’s very hot. Thinking back to my HS bio, I suspect it’s due to transpiration via the stomata on the undersides of the leaves.
Huh. And here I thought the answer was going to be “well, when a boy tree and a girl tree like each other very much…” and instead, they’re just sweating. Go figure.
It’s caused by those world-shadow-government chem trails visible near the end of the video that fall onto the trees then drip onto your skin to transmit your thoughts to the Large Hadron Collider where they accelerate to 99.9999999 per cent of the speed of light and are shot out a “ventilator” pipe in Switzerland to aliens in Andromeda so they’ll know how prepared we are for invasion.
Fog drip looks like the answer. It seems perfectly possible that water comes from the transpiration of the trees, and you might not see any visible fog.
There’s been high humidity there … 75% relative humidity as one ball park figure… what was it on that day ? It all depends on the time of day, because like the same air a few degrees cooler is higher humidity in relative terms…
It may be all four causes, the high humidity promotes the other three, being
insects trying to keep cool, or eat more, transpiration (water from the roots exiting the leaves) and condensation (water from the air condensing on leaves.)