General Question

ChocolateReigns's avatar

Why does the snow melt first around the trees?

Asked by ChocolateReigns (5599 points ) March 6th, 2010

Up here in mideastern MN, we’re having a warm stretch and the snow is melting. We have quite a few trees in our yard, and there are big circles around the bases of the trees. I googled it, and there was a question on Y!A that got answered as “trees release heat”. That was the only answer. Needless to say, it didn’t help.
I’m not the first one to notice this, am I? Does anyone know why this is?

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14 Answers

bhec10's avatar

Maybe there could be melted ice/snow (water) running down the tree, making that circle?

dpworkin's avatar

This is sap season, when huge volumes of fluid are being moved from the earth through the trunk and branches of the trees.

stranger_in_a_strange_land's avatar

The sap rising up from the root zone is significantly warmer than the ambient air temperature. This causes snow melt around the trunk.

becomingme's avatar

I’ve noticed that too!! Good question! I am also interested. :)

ChocolateReigns's avatar

I just found this on Answerbag (second result in google, just thought to look at it!):

snow is white it has a nearly 100% refractive effect from the surface area. Tree trunks are dark so the have a very high heat absobtion rate. This in turn causes the Sun’s heat to bounce off of the surface of the snow and be absorbed by the tree trunk, the tree heats up and radiates heat out ward in 360 degrees (around the base of the trunk) causing the snow there to melt first.
The branches overhead make it so there is less snow to begin with. Next to the tree there is a good water supply and this could make the ground slightly more moist which could cause the snow to melt faster.

jaytkay's avatar

Interesting. Check out the “tree ring” in this photo I took a couple of weeks ago.

stranger_in_a_strange_land's avatar

Even the heavy wind drift snow pulls away from the trunks. It’s the warm sap flowing.

dpworkin's avatar

(And @stranger_in_a_strange_land ought to know: he’s working in the sugarbush right now.)

ChaosCross's avatar

The snow and the tree get into a fight and the tree always wins the custody battle.

wilma's avatar

Mine are he same @ChocolateReigns It looks like you and @stranger_in_a_strange_land have got the answers. Good to know, and I’m getting ready to tap my sugar Maples now too!

CaptainHarley's avatar

Wood retains a degree of warmpth ( which is why it doesn’t freeze and split in extremely cold weather ), plus, most bark is dark in color, which means that it absorbs more heat from the surrounding air and from sunlight.

Cruiser's avatar

It’s the doggies peeing on the trees. The paw prints should be a dead give away.

stranger_in_a_strange_land's avatar

@ChocolateReigns Your pictures look like the rings were formed by water dripping off the branches. In the deep woods, with about three feet of snow still on the ground, the snow is actually melted away from the trunk itself, a different phenomenon, as the sap is being drawn up during the day from below the frost line (about four feet below the surface). So the snow melt around the trees is due to a combination of factors.
Being in an urban setting, @Cruiser s explanation has some merit also.

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