Cherry Orchard Choppers in -20?

Re: Cherry Orchard Choppers in -20?

Postby LANDM » Feb 14th, 2021, 8:19 am

bob vernon wrote:It's amazing how many genius physicists come out on here. If it is -20C at the ground level, is it also -20C at the top of the trees? How about 25 metres above the tops of the trees?


Actually, the genius physicists must be the farmers who have been protecting their crops in these ways for decades. Successfully.

Frost damage can cut like a knife during blossom time. Bottom of a tree..no fruit, too of the tree..normal.

Ground level temperatures can be, and often are, very different than the top of a tree, depending on conditions. During cold winter temperatures, as Glacier noted, massive air mixing from wind machines and helicopters can and do make the difference between a crop and no crop.
It’s amazing how many genius armchair-farmers come out on here. :130:
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Re: Cherry Orchard Choppers in -20?

Postby just_browsing » Feb 14th, 2021, 9:52 am

common_sense_guy wrote:
just_browsing wrote:Ok, I can see the rationale behind drying the cherries but tell me the science behind helicopters blowing -20 air around cherry trees? Does it make sure that they get destroyed for insurance purposes?

An insanely disruptive strategy during the summer months is now all year round?

I'm always curious why people choose to ask an internet forum when they know they're going to get 10 different answers instead of Googling it themselves.


I did google it and came up with NOTHING!
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Re: Cherry Orchard Choppers in -20?

Postby voice of reason » Feb 14th, 2021, 10:50 am

bob vernon wrote:It's amazing how many genius physicists come out on here. If it is -20C at the ground level, is it also -20C at the top of the trees? How about 25 metres above the tops of the trees?

if its -20c at the ground its not +5c 10ft above the ground

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Re: Cherry Orchard Choppers in -20?

Postby alanjh595 » Feb 14th, 2021, 11:20 am

Helicopters battling frost
Rob Gibson - Apr 15, 2020 / 4:00 am | Story: 297197

If you've been hearing helicopters at the crack of dawn over the past few weeks you're not alone.

Bruce Morrison sent us a short video and a few pictures of a low-flying helicopter in the East Kelowna area, "this morning (Saturday), starting at 6 a.m., there was a low-flying helicopter doing laps over an East Kelowna property and surrounding parks and structures until 6:50 a.m. They were an estimated 30 feet above the ground (and) were almost right above my vehicle at one point while parked on the shoulder of the road."

Okanagan residents are familiar with helicopters using their blades to clear off rain and dew build-up on cherries as they get closer to harvest, but perhaps have not heard that cherry farmers also use helicopters in the spring to ward off frost.

A local helicopter operator tells Castanet during some springs, in late March and early April, frost can damage cherry tree buds.

Once daytime temperatures begin to rise some cherry buds begin to flower, but if cooler temperatures follow the next day, especially in the morning, frost can kill the buds, damage the tree and set the growing process back.

High temperatures for Kelowna are expected to be in the mid-teens this week but the forecast for Wednesday morning is calling for a low of -1 C.

"The coldest part of the day is in the morning, that's why it's important to circulate the air in the morning," said the helicopter pilot, who has been flying in Kelowna for the past 10 years.

Hank Markgraf is a Kelowna orchardist and a board member with the International Tree Fruit Association and an orchardist, he says the technique has been used for the past 20 or 30 years in New Zealand and Australia but not so much here in the Okanagan.

"We haven't used (helicopters) them that much but we haven't had that many cold springs either. This is definitely a colder one for us for sure, it's been two or three years since we've had a cool spring like this one," says Markgraf.

Orchardists use the helicopters to move an inversion or to capture warm air hovering just above the orchard and push it back down into the orchard. Markgraf says it is relatively expensive to use helicopters but farmers weigh the cost of losing a portion of their crops versus the expense of hiring a helicopter.

"Our cherries are in that tender timing right now. The orchards have woken up but we still have cold temperatures in the morning."

Markgraf says the sounds of helicopters fighting frost will continue until we are through the cherry blossom season, "every morning that's below zero is a danger morning for us." The cold is a danger to all tree fruits, including vineyards, but cherries are ahead right now and farmers can typically get a higher return for cherries, especially in foreign markets.

"It's different for each tree fruit but as we know Canadian cherries right now are highly valued in the far east so they return a lot of money," says Markgraf.

Some orchardists also use wind machines to help control the average temperature in their orchards at the most critical times of the year.

Spring frost and winter freezes threaten stone fruit, like cherries, peaches, and apricots but wind machines and helicopters provide protection at crucial times of the growing season.

Some farmers even use drones as a means to measure the temperature and dispersal of air as it is pushed around orchards by these types of fans.


https://www.castanet.net/news/Kelowna/2 ... herry-crop
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Re: Cherry Orchard Choppers in -20?

Postby common_sense_guy » Feb 14th, 2021, 4:25 pm

Symbonite wrote:hmm never heard of this before....

Most logical..

They are doing training hours.

Thanks Spock
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Re: Cherry Orchard Choppers in -20?

Postby common_sense_guy » Feb 14th, 2021, 4:26 pm

voice of reason wrote:thats all fine and dandy but as soon as the chopper stops flying overhead the -20c air settles in again and the choppers fly for an hour or so out of the day. cherrys are going to be 100 bucks a pound and orchardists are going to have to start putting in helipads if this keeps up. so they get a couple hours of air movement during the warmest part of the day but then its dark for 12 hours when the choppers cant fly and the temps are the coldest. seems like a strange and costly plan

It may seem strange but obviously it must be necessary because they've been in the business for years and years and know what needs to be done to save their crop. Farmers of the last people that waste money unnecessarily for the most part
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Re: Cherry Orchard Choppers in -20?

Postby common_sense_guy » Feb 14th, 2021, 4:27 pm

Brushy Bill wrote:Those are the cherries destined for export to the Chinese market right ?
Owned by foreign investors? Maintained by tfw's ?
mmm fresh cherries .....

No
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Re: Cherry Orchard Choppers in -20?

Postby Terris » Feb 15th, 2021, 11:06 am

How many here remember seeing a more low tech solution implemented in the orchards here once upon a time? I certainly do...

https://www.bing.com/images/search?view ... ORM=IRPRST

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Re: Cherry Orchard Choppers in -20?

Postby 60-YEARS-in-Ktown » Feb 15th, 2021, 2:23 pm

I remember those being used on road construction in Edmonton.
And I know in Glenmore our neighboring orchard used much bigger square containers.
I am thinking the emphasis was more on heat, the round ones more for light..
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Re: Cherry Orchard Choppers in -20?

Postby LANDM » Feb 15th, 2021, 2:37 pm

Terris wrote:How many here remember seeing a more low tech solution implemented in the orchards here once upon a time? I certainly do...

https://www.bing.com/images/search?view ... ORM=IRPRST


Yes, smudge pots were very common. And they worked. Of course, the required carbon offset would get a bit silly, costwise. :D
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Re: Cherry Orchard Choppers in -20?

Postby Glacier » Feb 16th, 2021, 10:40 am

In the most extreme cases documented, you can have over 10C temperature difference in just 40m change in elevation, so in that instant, helicopters could increase the temperature by 10C. Keep in mind that every degree below -15 is causing damage for the up comng crop. Even increasing the temperature from -20 to -19 does a lot to lessen the crop damage. Raising the temperature to -17 does even more.

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Re: Cherry Orchard Choppers in -20?

Postby dirtybiker » Feb 16th, 2021, 10:50 am

Add in the heat emitted from a running engine along with
our trusted source of all things weather, Glacier.
Doubles down the difference betwixt success and
failure to crops produced.
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Re: Cherry Orchard Choppers in -20?

Postby Grandan » Feb 16th, 2021, 11:12 am

alanjh595 wrote:
Catri wrote:How then would the windchill created effect the buds when -20 air is propelled at 40kph?
Windchill doesn't affect things like trees in the same way it does us warmblooded creatures. In simple terms the reason air feels colder to us in the wind is that it carries away the heat that our bodies radiate to try to keep us warmer than the air temperature. Plants/trees don't generate heat so they don't lose heat to the wind. It's the same reason that a thermometer reading doesn't reflect wind chill.


That is correct.
Thermal dynamics 101.

There are three different means of heat transfer.
Conduction
Convection
Radiation

Just consider typical household cooking.
Conduction is the burners that you put a pot on.
Convection is the oven, and to make that even more efficient, a convection fan that moves the air around in the oven, radiation is from a microwave.


conduction
heat transfer through stationary matter by physical contact
convection
heat transfer by the macroscopic movement of fluid
radiation
heat transfer which occurs when microwaves, infrared radiation, visible light, or other electromagnetic radiation is emitted or absorbed


https://pressbooks.bccampus.ca/introduc ... 0radiation.[/quote]
The radiant heat is what you get when you put your steak under the top broiler in a conventional oven. Microwaves work differently, the radiation excites the molecules in the target object and that is how the heat is generated. Microwaves cook from the inside out, broilers heat from the outside in.
Waste not

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Re: Cherry Orchard Choppers in -20?

Postby alanjh595 » Feb 16th, 2021, 11:24 am

Well.....sort of.

In a microwave......the outside edges cook first, that is why the center of a plate of food is cooler in the center that it is on the outer edges.

To test my theory, put a frozen hamburger patty on a plate and into a microwave. I guarantee that the results will prove it.
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Re: Cherry Orchard Choppers in -20?

Postby Grandan » Feb 16th, 2021, 11:25 am

cv23 wrote:How exactly are helicopters doing anything beneficial to the fruit crop? It's not an inversion layer situation or frost pocket. It's -10 to -20 for days in a row not just a few minutes or hours.

On any given day the temperature on my ground level at the front of my house is several degrees warmer than it is at my walkout basement level a mere 10 ft lower.
Air temperatures over night are a strata with the lowest temperatures at ground level. Also ground that is sloped toward the north have lower temperatures because heat is radiated into space. The coldest temperatures are generally just before dawn which is why the helicopters are active at that time. once in daylight the temperatures rise due to solar radiation and the stratification of cold air starts to reverse with the ground heating up to reverse the phenomenon that happens overnight.
Do you think orchardists would waste their money on a strategy that does not work?
Waste not

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