Please read the posts in the Announcements section about the current status of Cumulus development now that I have retired

Please read this post before posting

Latest Cumulus release v1.9.4 (build 1099) - Nov 28 2014
Latest Cumulus MX release - v3.0.0 build 3043 Jan 20 2017. See this post for download

Radiation Shield accuracy

Discussion specific to Davis weather stations
RayProudfoot
Posts: 2405
Joined: Wed May 06, 2009 6:29 pm
Weather Station: Davis VP2 with Daytime FARS
Operating System: Windows XP SP3
Location: Cheadle Hulme, Cheshire, England
Contact:

Re: Radiation Shield accuracy

Postby RayProudfoot » Fri Mar 26, 2010 7:37 pm

Ths looks ideal for the 6ft post. http://www.alfresia.co.uk/50mmsoilspike.html
Cheers,
Ray, Cheshire.

Image

User avatar
mcrossley
Posts: 5006
Joined: Thu Jan 07, 2010 9:44 pm
Weather Station: Davis VP2
Operating System: Jessie Lite rPi
Location: Wilmslow, Cheshire, UK
Contact:

Re: Radiation Shield accuracy

Postby mcrossley » Fri Mar 26, 2010 9:42 pm

Ray, B&Q at Handforth have 32mm aluminium aerial poles in stock at various lengths.

RayProudfoot
Posts: 2405
Joined: Wed May 06, 2009 6:29 pm
Weather Station: Davis VP2 with Daytime FARS
Operating System: Windows XP SP3
Location: Cheadle Hulme, Cheshire, England
Contact:

Re: Radiation Shield accuracy

Postby RayProudfoot » Fri Mar 26, 2010 9:59 pm

mcrossley wrote:Ray, B&Q at Handforth have 32mm aluminium aerial poles in stock at various lengths.

You can't beat local knowledge! :clap: Thanks Mark!
Cheers,
Ray, Cheshire.

Image

Pete B
Posts: 28
Joined: Mon Mar 08, 2010 9:59 am
Weather Station: Davis VP2 Wireless
Operating System: Windows XP Home SP3

Re: Radiation Shield accuracy

Postby Pete B » Fri Mar 26, 2010 11:52 pm

This was the ground spike I used. The ID of the steel tube of the spike is 38mm, reducible to 32mm with a plastic sleeve where required. I also purchased 2 x 3m long, 38mm (1.5in) dia, galvanised steel poles from a local aerial installer. I cut one of these in half and used it mounted in the ground spike to mount the ISS minus the anemometer to at the std 1.25m above grass. As I said elsewhere, I also cut a slot across the diameter of the ground spike 3 cm along the spike so I could clamp the post tightly using a 'Jubilee' clip. The extra advantage of this is that thin spacers can be slid down between the post and ground spike to finely adjust the post/ISS to get the mounted ISS exactly level. In my case, I didn't need to do this, by repeatedly checking the spike for vertical alignment while driving it into the ground was sufficient.

The remaining half pole length, joined together with the other 3m long pole was used to mount the anemometer to, mounted on brackets on the side of the garage wall where I can easily get to it for lowering the anemometer for maintenance. This puts the anemometer above the roof apex and being steel, the poles are stiffer than Al of the same diameter and don't move around so much in the wind. Also, for rigidity, the larger the diameter, the better.

User avatar
Super-T
Posts: 786
Joined: Tue Sep 09, 2008 3:37 am
Weather Station: wh-1081
Operating System: Weather Laptop - Windows 10 Pro
Location: Auckland, New Zealand
Contact:

Re: Radiation Shield accuracy

Postby Super-T » Sat Mar 27, 2010 1:23 am

You can purchase 4 or 5 metre lengths of aluminium, square section tubing from any local aluminium supplier. My mast for the anemometer and vane are mounted on a 5 metre length 40x40 Aluminium tube. This tube is mounted to the stairway railing on the upper deck so the top is probably close to 7.5 Metres above ground. Doesn't seem to need stays yet but we haven't had much over 50KPH winds yet. Transmitter unit is sitting under the eaves of the house directly below the mast. Top of the mast is still only just level with the top of the roof so I am sure it still gets turbulence but is good enough for me.
Forum software doesn't like my English spelling of some words? Is it set for US spelling?

RayProudfoot
Posts: 2405
Joined: Wed May 06, 2009 6:29 pm
Weather Station: Davis VP2 with Daytime FARS
Operating System: Windows XP SP3
Location: Cheadle Hulme, Cheshire, England
Contact:

Re: Radiation Shield accuracy

Postby RayProudfoot » Sat Mar 27, 2010 11:49 am

Pete,

Thanks for the detailed guide to your installation and the link to the post you used. That and the Minky one I'm contemplating don't seem too different in design. As my soil is clay I'm confident that one the post is level it won't shift. My anemometer is attached to the top of an 8ft pole strapped to my chimney so that side of things is fine. I just need the weather to warm up so the garden can dry out a bit. :(
Cheers,
Ray, Cheshire.

Image

RayProudfoot
Posts: 2405
Joined: Wed May 06, 2009 6:29 pm
Weather Station: Davis VP2 with Daytime FARS
Operating System: Windows XP SP3
Location: Cheadle Hulme, Cheshire, England
Contact:

Re: Radiation Shield accuracy

Postby RayProudfoot » Sat Mar 27, 2010 11:50 am

I hope this thread doesn't deviate too much as it's proving an excellent guide for station accuracy. Let me just paste this from Wikipedia and hope it clears up any ambiguity about the spelling and pronunciation of aluminium (aluminum)....
Most countries use the spelling aluminium (with an i before -um). In the United States, this spelling is largely unknown, and the spelling aluminum predominates.[54][55] The Canadian Oxford Dictionary prefers aluminum, whereas the Australian Macquarie Dictionary prefers aluminium.

The International Union of Pure and Applied Chemistry (IUPAC) adopted aluminium as the standard international name for the element in 1990, but three years later recognized aluminum as an acceptable variant. Hence their periodic table includes both.[56] IUPAC officially prefers the use of aluminium in its internal publications, although several IUPAC publications use the spelling aluminum.
Cheers,
Ray, Cheshire.

Image

User avatar
steve
Cumulus Author
Posts: 26300
Joined: Mon Jun 02, 2008 6:49 pm
Weather Station: None
Operating System: None
Location: On tour in Spain
Contact:

Re: Radiation Shield accuracy

Postby steve » Sat Mar 27, 2010 11:52 am

I've moved the sub-thread about spelling into the "general" forum.
Steve
-----
Hosting available for Cumulus web sites. See http://sandaysoft.com/forum/viewtopic.php?f=2&t=11876

Please read the posts in the Announcements section about the current status of Cumulus development now that I have retired

Pete B
Posts: 28
Joined: Mon Mar 08, 2010 9:59 am
Weather Station: Davis VP2 Wireless
Operating System: Windows XP Home SP3

Re: Radiation Shield accuracy

Postby Pete B » Sat Mar 27, 2010 11:29 pm

As promised, some photo's of my ISS setup.

Garden with ISS.JPG

This shows the position of the ISS mounted on the pole relative to the side fences and the fence at the bottom of the garden. The top of the ISS white shielding is 1.25m above the grass. Those trees well behind the end of garden fence will become a green shield in a couple of months time, totally blocking out the houses and maybe will have some effect on humidity & sunshine measurements.


House behind ISS.jpg

This shows the ISS relative to the back of the house. The brackets and pole on the side of the garage is the bottom of the pole that the anemometer is mounted on.


ISS Closup.JPG

This shows the pole & ISS closeup. The transmitter unit below the ISS is a leaf & soil unit with a single temperature sensor feeding into it that is positioned to measure the grass temperature.

The poles are 38mm (1.5in) O/D galvanised steel.
You do not have the required permissions to view the files attached to this post.

RayProudfoot
Posts: 2405
Joined: Wed May 06, 2009 6:29 pm
Weather Station: Davis VP2 with Daytime FARS
Operating System: Windows XP SP3
Location: Cheadle Hulme, Cheshire, England
Contact:

Re: Radiation Shield accuracy

Postby RayProudfoot » Sun Mar 28, 2010 9:01 am

Hi Pete,

Thanks for the photos. That's an excellent location for the ISS. The frustrating thing for me is that I could position mine in the middle of the lawn but I don't want to make it difficult for the gardener. If he were to nudge it and knock it off level he would probably not think anything of it but my rain readings might go haywire.

So I'm still looking at a spot near the shorter fence but after I switch to an aluminium pole and position the ISS around 5-6ft it will be sufficiently high enough for any heating effect from the fence to be minimal. And of course I won't have any heat coming off the pole as I probably do with the wooden post at present.

How long is the pole holding the anemometer? Does it clear the roofline?
Cheers,
Ray, Cheshire.

Image

adam5
Posts: 56
Joined: Thu Nov 19, 2009 3:22 am
Weather Station: Davis Vantage Pro2
Operating System: Windows XP SP3
Location: Gaylord, MI, USA
Contact:

Re: Radiation Shield accuracy

Postby adam5 » Sun Mar 28, 2010 4:16 pm

But knowing what is natural warming (a warm garden) and what is false warming (post generating heat up to the sensor) is difficult to determine.

That is so true, and perhaps something you will never be completely sure about. Don't get me wrong, as I stated before I admire the persistence and drive for "perfection" in taking temp measurements...I do the same thing. I only made those comments for the sake of your own sanity.

RayProudfoot
Posts: 2405
Joined: Wed May 06, 2009 6:29 pm
Weather Station: Davis VP2 with Daytime FARS
Operating System: Windows XP SP3
Location: Cheadle Hulme, Cheshire, England
Contact:

Re: Radiation Shield accuracy

Postby RayProudfoot » Sun Mar 28, 2010 9:53 pm

adam5 wrote:That is so true, and perhaps something you will never be completely sure about. Don't get me wrong, as I stated before I admire the persistence and drive for "perfection" in taking temp measurements...I do the same thing. I only made those comments for the sake of your own sanity.

Hi Brian,

The more I look at the airport temperatures the more I'm convinced I should just ignore them! :roll: Otherwise the blokes with white coats will be taking me away! :bash: After all, it's not rocket surgery getting the station in the right place!! :lol:
Cheers,
Ray, Cheshire.

Image

Pete B
Posts: 28
Joined: Mon Mar 08, 2010 9:59 am
Weather Station: Davis VP2 Wireless
Operating System: Windows XP Home SP3

Re: Radiation Shield accuracy

Postby Pete B » Mon Mar 29, 2010 10:17 pm

RayProudfoot wrote:Hi Pete,

Thanks for the photos. That's an excellent location for the ISS. The frustrating thing for me is that I could position mine in the middle of the lawn but I don't want to make it difficult for the gardener. If he were to nudge it and knock it off level he would probably not think anything of it but my rain readings might go haywire.

So I'm still looking at a spot near the shorter fence but after I switch to an aluminium pole and position the ISS around 5-6ft it will be sufficiently high enough for any heating effect from the fence to be minimal. And of course I won't have any heat coming off the pole as I probably do with the wooden post at present.

How long is the pole holding the anemometer? Does it clear the roofline?


Anemometer Setup.jpg

This photo shows the anemometer setup, against the roofline. The anemometer is about 4m this side of the main roof wrt where I took the photo from so it is reasonably clear of the roof. Obviously, it would be better on a shorter pole mounted right at the apex on the main wall near the TV aerial but I haven't the head for those heights any more (once upon a time I may have done it).

Natural tall green 'plants' exists in large amounts round here higher than roofs and, at least in Summer, will have more efffect than the roofs anyway. I have about another 20cm of pole 'free' below the bottom of the lower bracket so I could raise the pole further by that amount without any problem.

I have one slight concern for the main ISS pole. Since like you, the soil here is mainly clay, I'm thinking whether in hot dry weather, the soil will dry and contract leaving the pole & ground spike a little loose in the ground. Only time will tell.
You do not have the required permissions to view the files attached to this post.

RayProudfoot
Posts: 2405
Joined: Wed May 06, 2009 6:29 pm
Weather Station: Davis VP2 with Daytime FARS
Operating System: Windows XP SP3
Location: Cheadle Hulme, Cheshire, England
Contact:

Re: Radiation Shield accuracy

Postby RayProudfoot » Mon Mar 29, 2010 10:58 pm

Hi Pete,

Thanks for the pic of the anemometer. My first thought is why is the transmitter so high? Would it not be more accessible closer to the ground? There is enough cable. Fully understand your reluctance to place the ane so high it becomes difficult to access. I took the decision to have mine fitted by an aerial guy but it does mean I need to get him around when it malfunctions. Time will tell if I made the right decision.

I've been thinking about the round aluminium pole fitting in a round spike. To remove the rain guage you have to twist it with quite a bit of pressure. There could be a danger that the pole rotates with it. That would not be good. That's one advantage of post mounting. Is it securely fitted inside the hollow spike? Have you had to remove the gauge yet for cleaning and if so, was it a problem.

We'd have to go a long time without rain for clay to dry out. I think you'll be okay.
Cheers,
Ray, Cheshire.

Image

User avatar
steve
Cumulus Author
Posts: 26300
Joined: Mon Jun 02, 2008 6:49 pm
Weather Station: None
Operating System: None
Location: On tour in Spain
Contact:

Re: Radiation Shield accuracy

Postby steve » Tue Mar 30, 2010 6:57 am

Can I ask you chaps where you bought your remote anemometer transmitters? I'm thinking of getting one so I can relocate my anemometer, but they seem quite expensive. I was thinking of importing from the US, but I think the frequency would be wrong. Exchange rate isn't good, either!
Steve
-----
Hosting available for Cumulus web sites. See http://sandaysoft.com/forum/viewtopic.php?f=2&t=11876

Please read the posts in the Announcements section about the current status of Cumulus development now that I have retired


Return to “Davis VP/VP2/Vue”

Who is online

Users browsing this forum: Google [Bot] and 5 guests