Outdoor thermometer placement

[Vic Smith]

In that case you need the sensors at the trees.

[Snuffy "Hub Cap" McKinney]

Put one sensor on the inlet to the HVAC, and another one under a citrus tree. If you're worried about the sun affecting it, add something like an umbrella.

[Muggles]

Yeah. That's makes sense.

[Phil Kangas]

"Don Y"

As the morning dew evaporates it absorbs a lot of heat, that's why it is cooler. Simple as that ... no brainer... phil k

[Tony Hwang]

MY Davis weather station is on a ~10 feet pole in the front yard, one thermometer inside the screened patio hanging from the ceiling. Indoor has thermostat one.

[clare]

Put it inside a 3 foot long 6 inch white plastic pipe, at least 3 feet off the ground and open at both ends. Mount the thermometer in the center of the pipe. Of course this only works for remote reading thermometers.

[clare]

"it is always darker just before dawn" Any residual heat has run out and the heat of the sun has not yet arrived - Generally the coldest time of the night is after 3am and before 7am.

[Don Y]

That's possible if there is dew (frost) on the mountain; there's nothing *here* at its base! That would also be more consistent with the timing: we are often not yet in sunlight -- but the south-facing slope of the mountains immediately to our north is!

It would also explain why the phenomenon is local to our immediate area and not (as much) for folks several blocks further south (higher elevation)

[Don Y]

Trees are within 10-20 feet of the house. So, there's likely no difference in temperatures there vs here IN THE ABSENCE OF MAN-MADE INFLUENCES.

Locating them at/in the trees would expose them to the daytime sun.

For example, I was outside a few minutes ago checking the fruit. I moved a thermometer (not a wired sensor) from it's location on the porch out into the yard -- 12 feet away. In the time it took for me to walk to three of the trees and back, the registered temperature had climbed from 51F to 72F. (I'm *sure* the air temperature hadn't changed that much! :> )

Nearby weather reporting sites range from ~47F to ~57F. The closest to my location (unsure of its relative elevation) reports 50F -- which is in line with my 51.

[My 51 is usually high due to its location in a "heat trap"]

[Don Y]

Not a "grove", just half a dozen trees.

There's only so much we can realistically do; can't deploy smudge pots as there are too many structures nearby; can't deploy fans as the trees aren't arranged in a "grove" (we'd need several small fans, instead).

We opt to cover the trees and use small heat sources to help encourage convective air flow (has to work in case it's also raining).

I've covetously eyed the "blow up figures" that folks put out for holiday decorations thinking that I might be able to repurpose the fans used in them. They *should* be able to tolerate rain, right?

OTOH, they are covered by a large inflatable fabric sack so I'm not sure how well they actually fare in a downpour! (do people actually have them inflated when its raining??)

The more practical solution is to move to higher ground farther from the wash.

Or, stop growing fruit that doesn't like the weather!! :>

[I've repeatedly threatened SWMBO that when the next REALLY cold spell comes through and whacks the trees, I'll use them in the smoker!! :> ]

[Paintedcow]

I have a tree about 6ft. from a house window. I put a thermometer on the tree. During rain, water ran down the tree trunk and would get inside the thermometer. I finally drilled a hole in the bottom of the plastic front of it to let the water drain out, but eventually it ruined the thermometer. Now I have a new one, but I mounted it on a board, put a piece of tin at the top of the board to hang over the thermometer and divert the water away from it. Then I screwed the whole board to the tree. I hope this works better.

[Paintedcow]

In a small nearby town, there are 4 signs with the temperature. (2 banks, one gas station, and a community sign). NONE of them are ever the same. They vary by as much as 6 deg. All of them are within one half mile. I compared them to my cellphone weather, and the gas station is always the most accurate (and it's also the newest sign). No thermometer is 100% accurate.....

[Micky]

Right. If I want to know the exact temperature, I go outside.

It's also darkest just before the dawn! So I hear.

[Mayayana]

| I'll often just touch the window to see how cold it feels to gauge how | many layers of sweater and coat I need before going outside. |

Hopefully you don't end up getting double insulated glass. You could freeze to death. :)

[Micky]

Luddite!

[clare]

Or worse yet - tripple glazed windows>

[dpb]

I've not been to grandparents' old place in TX Valley in years to know what they now use (of course, it's two-three generations removed from grandparents now) but for temp measurement I'd think you'd get by pretty nicely with just a covered box near where you really need the detail info; as you point out if you're really after that local micro-difference to protect individual tree(s) it may not be enough unless you go for it in an all or nothing fashion whenever you do get an indication (likely the most reasonable alternative). But, as another I think noted, I've got a Davis Instruments weather station that seems to be quite accurate simply with the sun shielding they come with "out of the box" -- it sits out in the midday sun in SW KS at 100+ F w/o measuring ridiculously high temps that occur from directly-exposed thermometers.

The standard thermometer on the north side of the house at the top of the porch also has always seemed pretty good -- it's 8' or so, roughly from actual outside wall of the house so the heating effects don't seem very influential as far as can tell...

[Don Y]

Radiate heat from the (masonry) house isn't the problem, IMO. Rather, it is the heat trapped under the roofline that elevates the temperature registered by the thermometer/sensor.

I would like to come up with a "solution" that others can recreate (as I assume others will be interested in much of the technology that I've developed -- and I'm not interested in going into manufacturing! :> )

COTS "weather stations", IME, are just "curiosities". They give the user/owner a sense of what the weather is like -- without having to be precise (note "precise" and "accurate" have different technical meanings).

E.g., an indoor thermometer doesn't have to be accurate at all! Do you *really* know if it is 68F in the house? 71? What's the temperature at the other end of the hallway? In the kitchen? etc.

All you want from the "thermostat" is to keep the temperature AT a particular point -- and, some way of referring to that point (we could call it "foogle" just as easily as "68") as well as points ABOVE and BELOW ("elgar" is just below "foogle" and "gismatch" is just above! :> )

OTOH, if you know that a particular fruit is hardy to 32F (or 28F), then you don't want to play guessing games wondering if 32 is "elgar", "foogle" or "gismatch"!

You also want to know the *actual* relationship between these so you can perform reliable mathematical operations on them: "How much energy do I have to expend to create a local "foogle" microclimate when the outdoor temperature is "elgar"? Or, "dingbrill"? At which point will I no longer be able to influence the microclimate based on these calculations??

[Someone with the sort of interest I'm concerned about will be willing to sort out *proper* placement of a sensor instead of just relying on what's convenient]

[dpb]

On 12/28/2015 11:54 AM, Don Y wrote: ...

Well, if you're really thinking you're going to get into it in that depth, then there's a _ton_ of research already done and a large fraction of it illustrates that simply knowing air temperature (no matter how accurately) ain't _nearly_ enough to reliably predict damage.

[Don Y]

Correct. That's why I also note wind speed/direction, barometric pressure, solar radiation along with azimuth/elevation, dew point, etc. I'm not looking for a "toy" that just throws numbers at a casual user/hobbyist but, rather, a genuine control system! :> The extent of control depending on how much the user is willing to "invest" in instrumentation.