They do not work by heating the air. They work by producing a heavy smoke layer over the orchard which reduces the heat loss by radiation to the night sky.
are smudge legal in california
eBay or your local classified advertisements are the best bet, since I don't think there are any US manufacturers anymore. Smudge pots are such an environmental nightmare, and there are much better and more cost-effective methods available. Simply starting up water sprinklers over the trees when there is frost danger will take care of them as well as smudge pots would. Orchard fans are another possibility.
If you have cedar trees in pots that keep dying, you probably need to repot the trees. They probably need more room in order to survive.
You may be referring to the use of smudge pots which is a method of using oil burning heaters in orchards to prevent freezing of the crops.
A small smudge
A small smudge
The plural of smudge is smudges.
A small smudge
Smudge isn't a Moshling.
The plural form of "smudge" is "smudges."
there was a smudge on the famous painting
Smudge