North American Fruit Explorers mailing list at ibiblio

[Steve <sdw12986@aol.com>]

I understand the different types of frost. I was just objecting to "The cool soil chills the air above it lowering the air temperature."
While certainly cool soil could lower the air temperature if the air is warmer than the soil, that's not an issue when frost is the worry. If the air and plant surfaces are approaching the freezing point, how could the soil itself be making the air cooler unless the soil is already below freezing. If the soil is still frozen, I don't think anything is growing yet anyway.
Soil is going to give up its warmth and prevent frost until it can't keep up with the cooling, whether from radiation or advection. The rest of the article was just fine and correctly pointed out that bare ground gives up more heat (therefore more protection) than soil insulated by a cover crop.




dmnorton@royaloakfarmorchard.com wrote:

Steve,

 

There are many types of frost, radiation frost being one of them. Visit  http://www.weathernz.co.nz/FrostInfo.html to see the various conditions that can create the various types of frost.

 

Dennis Norton
Royal Oak Farm Orchard
http://www.royaloakfarmorchard.com
http://www.theorchardkeeper.blogspot.com
http://www.revivalhymn.com

----- Original Message -----

From: Steve

To: North American Fruit Explorers

Sent: Thursday, March 20, 2008 8:12 PM

Subject: Re: [NAFEX] Bare ground is warmer

dmnorton@royaloakfarmorchard.com wrote:

The following short article appears in the current Fruit Crop Advisory Team newsletter form Michigan Sate found at http://www.ipm.msu.edu/cat08fruit/f03-18-08.htm.  Thought some of you might find it interesting, especially those of us in the colder zones approaching late frost season.

 

Bare ground is warmer
Mark Longstroth District Extension Fruit Educator

March 18, 2008 -- Spring frosts are a worry for fruit growers. Radiation frosts occur when clear calm conditions during the night allow the ground to cool by radiation to the sky. The cool soil chills the air above it lowering the air temperature.   ............................................

Say what?
He makes it sound like the cold is coming from the ground.
The author obviously knows what he is talking about, judging from the rest of the article. I think he would rewrite that last line above if he was questioned on it.

Steve