How to measure freezing on buds

[Yveaux]

@gohan I guess the objective is to prevent them from freezing, by e.g. spraying water on them just before they freeze.

[NeverDie]

Unless there's a sensor that can detect frost damage (maybe a color sensor?), a temp sensor wired to your buds seems about all you can measure.

[pierrot10]

@yveaux Hello.
How would you put a temperature sensor into a buds and be certain that the sensor will only monitor the bud temperature and not the ambiant temperature?

Then I am not an expert as well, but one of my friend told me, they can spray a product over the bud and keep the bud temperature at 1-2C while the ambiant temperature goes below 0C

He told me, an equation exist, which take in consideration the humidity and the ambiant temperature to know the bud status.

But I was wondering if there is existing solution to monitor specially the buds temperature?

[scalz]

But is temperature sensor only enough? I don't think the sensor really needs to be sticked to the bud (I can be wrong)
Search for sensors&formulas about dew point, relative humidity and temperature.
or psychrometer concept, might not be very difficult to tinker a proto, and tests, calibrate etc

[mfalkvidd]

A common method for protecting grapevines is to have a big fan/propeller (wind machine) and start circulating the air.
https://youtu.be/mUrxKfDEglc

http://www.wine-grape-growing.com/wine_grape_growing/vineyard_frost_protection/vineyard_frost_protection_active.htm has some more information. Maybe the same methods can be applied to buds? That page says that the wind machine is usually powered on at 1-0 degrees C (32-34F)

[nagelc]

Maybe you could look at a few buds with an IR sensor -- a simpler version of this:
https://www.adafruit.com/product/3538

[sglue]

Question is, why would you want to "watch and measure the buds" freeze?
It would be too late to save your crops.

Leaf and Bud Temperature Sensor Features
https://www.apogeeinstruments.com/leaf-and-bud-temperature-sensor-features/

Google "how to measure bud freezing point" lots of info.

[alowhum]

Use infrared, as @nagelc proposed?

For example:
https://www.aliexpress.com/item/MLX90614ESF-DCI-Sensor-Module-MLX90614-Infrared-Temperature-Sensors-GY-906-DCI-IIC-Connector-Long-Distance-Electronic/32840909999.html

or more basic:
https://www.aliexpress.com/item/GY-906-BCC-MLX90614ESF-BCC-IR-Infrared-temperature-measurement-module-temperature-gradient-compensation/32611718585.html

[sglue]

@pierrot10 said in How to measure freezing on buds:

How would you put a temperature sensor into a buds and be certain that the sensor will only monitor the bud temperature and not the ambiant temperature?

Quickest way is to cut a bud/s and wrap in cotton wool or gauze with a temp. sensor and wrap tight with cling wrap (measure bud temp.)
Stick it in a plastic container with a temp. sensor (measure outside temp.) and put the whole the container in a freezer with a temp. sensor
Don't have to wait for winter.

[gohan]

The problem is that temperature alone doesn't cause the freezing. When there is clear sky things on the ground can get 2 or 3 degrees colder than air temperature because of a specific infrared radiation window that is radiating heat into space more than it is absorbing from the atmosphere. That's why a good forecast is normally needed

[pierrot10]

Thank for all of your replies
@gohan and @sglue Yep, it's was I found here radiation frost
So, normal temperature is not enough

Question is, why would you want to "watch and measure the buds" freeze?
It would be too late to save your crops.

The idea is to alert the owner before the critical point. But now, if there is only 2-3 degree of difference with the air temperature, will the owner interrested to watch the bud temperature. If he has a fun as show @mfalkvidd on the picture, we may better have a soli temprature which will turn on the wind turbine when the soil is close to 1-2C?.

In any case, if the owner crop is alerted when the temperature is closed to 1-2C, will he have time for an action? I guess, he will prepare the protection for the winter. Isn't?

(I am not farmer)
Thank to all. I will continue investigating with

Google "how to measure bud freezing point" lots of info.

[pierrot10]

This can be very interesting to meaure surface temperature
SI-111. but what's the price?

[nagelc]

The sensors @alowhum posted are much better than the AMG8833 IR sensor used by Adafruit for determining the bud temperature. Same idea, but much better for this application. The AMG833 is meant for detecting humans: 0°C to 80°C (32°F to 176°F) with an accuracy of +- 2.5°C (4.5°F).
Would not be a good choice for determining temperatures near freezing.

[JohnRob]

I'm not in agriculture but I am familiar with thermal radiation an normal heat flow. I had investigated thermal radiation some time ago and I recall a clear sky "looks" like -40 °C (or °F at this temp).

I would think for a bud to freeze it would depend on:

1. combination of temperature and time at temperature.
2. radiant cooling added into the effect of #1

I don't have any experience to suggest an actual solution. However I would consider thermal sensors (probably 1-wire) located at different places in the field, as well as some measurement of sky radiation.
These coupled with the time of day and some integral of time at temperature should be a good start.

[NeverDie]

Are there sensors for measuring sky radiation? That could be interesting. Here we do sometimes have to cover outdoor plants to keep them from freezing in the winter, but we rely on forecasts for that.

[scalz]

@NeverDie pyranometer??

[NeverDie]

@scalz said in How to measure freezing on buds:

pyranometer

Heck if I know. Doesn't that just measure the intensity of solar energy reaching the earth's surface?

[NeverDie]

@scalz Maybe this: https://en.wikipedia.org/wiki/Net_radiometer I'm not sure if it's overkill, but it does look like it would do the job. :)