barometric pressure

[sugardaddy's]

If this has already been discussed just re-direct me to the thread.
Does dropping barometric pressure increase sap flow?

[happy thoughts]

My hubby and I were just wondering about this the other day because it seems like the days we have had the better sap flows (when the proper freeze/warming conditions are met first) are when rain is forecast. Rain usually means a drop in the barometer. I found this link that may explain it though you'll have to make some inferences.

http://www.massmaple.org/sap.php

In order for sap to flow the pressure in the tree must be higher than the atmospheric pressure. If enough tree pressure exists for sap to flow then a drop in the barometer increases the difference between the tree and the atmosphere with the tree pressure winning. Under those conditions it would make sense that sap will flow better when the atmospheric pressure is lower, again assuming all the other conditions needed for sap flow are met first.

Next year I'm going to try to keep better track of weather conditions including barometric readings.

[mapleack]

Yes it helps. This is why vacuum in tubing makes a difference. It artificially creates a pressure drop between inside the tree and in the tubing.

[highlandcattle]

We have a weather station(you can get them at Walmart, even though I hate that place) or on-line) Ours can get info onto our computer, but it's wall mounted and I just keep writing down the readings. Also try NOAA weather for your location, gives the best forecast. Happy sapping! It's finally running here! Montgomery County, NY