Post a Pic of Your Weather Station

As an experiment, I've also placed out a completely unshielded temp logger right by the hospital in a place that doesn't get direct sunshine anytime during the day. It's obviously got a ridiculous micro-UHI by normal standards, being surrounded by buildings to all sides, walls just 1.5 meters away, and without any grass for dozens of meters in any direction. However, since there's no direct sunlight anyway near the thermometer, I don't expect it to matter all that much. Neither walls nor asphalt/gravel matter much unless they're hit by direct sunlight. I'd even argue that asphalt is a more meteorologically accurate surface than grass if the station is placed in the shade, because grass, that isn't even hit by sunlight, is going to be a fair bit colder than the ambient air temperature (whereas in an open spot grass is better since it keeps the ground from warming up too much compared to the ambient air during sunshine).

I've got some interesting initial results.
PWS 1 is the dyi radiation shield thingy, PWS 2 is the "naked" temperature logger in the shade. Looking at the far left of the chart, you'd think there was some serious inaccuracy, but the airport had actually recently made a 3'C temp drop in the last hour, and PWS 1 was in line with the uni station (slightly cooler even). Between 15 and 16 yesterday there was a 1'C discrepency between the diy radiation shield PWS 1 and the shaded PWS 2. I don't know if this was due to over-reading due to insufficient radiation cover, or if it's simply due to the sheltered and shaded location of PWS 2 not being able to rise as quickly in temperature during sunshine compared to a station placed in sunlight where the warm air can rise freely from the sunlit ground. Interesting night differences during this clear night, and interesting how similar PWS 1 and PWS 2 were today until 15:40 when PWS 1 tipped over and started recording temps 10 cm above ground until I fixed it around 21:00. If you'd only compare PWS 1 and the airport, you'd think PWS 1 is over-reading heavily and would be unusably inaccurate, but since PWS 1 and PWS 2 seem very much in line with eachother (with PWS 2 showing a slight delay in temps), I'm not sure the discrepency compared to the airport is due to insufficient radiation shielding, or else the shaded PWS 2 would be significantly cooler than PWS 1. Also, there's a large tree close to PWS 1 which means it's shaded for a short time sometime before noon. If the difference compared to the airport were to be due to insufficient radiation shielding, you should be able to notice a significant dip reflecting the time spent in the shade, but there isn't really anything that sticks out on the chart. Also worth mentioning is the Uni station has been the same or slightly warmer than PWS 1 pretty much every time I've compared the two.


Some of today's stats:

I was starting to worry I might have serious issues with radiation shielding on my station, because the last few sunny days my station has recorded highs multiple degrees warmer than the airport, and even up to a degree warmer than the Uni station. Today my station recorded 17.3'C, while the Uni station only recorded 16.3'C, and the PWS just west of Umeå's border only recorded a high of 15.6'C. The warmest hourly reading at the airport has been below 15'C too.

This is the current placement of the station. I moved it slightly so that I'd have a clear line of sight from my balcony. As you can see it's about 8 meters away from the road, and pretty near some (bare) bushes (the tall bushes look like they're closer to the station than the actual 2-3 meters). It's also about 1.5 m high which is within the WMO standard but lower than the more typical 2.0 m.


I checked with a grill thermometer and when placing the thermometer right underneat the station (in its shade), the thermometer would read about the same or warmer, and when I inserted the thermometer probe inside the radiation shield it would read the same or slightly lower. Of note is that the temperature could easily vary by a whole degree within a 50 meter area when I walked around with the thermometer in the shade generated by my own body. And as soon as there was a gust of wind, the temps could drop by up to 2 degrees.

My conclusion is that there is a vast difference between the temperature >5m up in the air, and the air closer to the ground, and any wind mixing the air will dramatically decrease the 1.5-2m temps. Likewise, areas with dry grass or leafy ground will be substantially warmer than places just a dozen meters away with wet ground from nearby snow piles or recent snowcover. Winds could be absolutely non-existant for quite long periods of time, allowing hot thermals from dry ground to rise and increase 1.5-2m temps really dramatically. Thus I actually do trust the readings from my PWS. However, as I biked around the area (holding the meat thermometer), I did notice that most places were a degree cooler than the particular spot where my station is placed, either because of more recent snow cover or, counterintuitively, because of too many houses nearby. I noticed the more densely built neighborhoods had cooler temps which I believe is because most of the sun's rays strike the sides and tops of the buildings, leaving the ground mostly in shade (and so while 5m temps were probably warmer, the 2m temps weren't as warm).

I suspect the cool airport temps is due to all the nearby fields having snowcover until perhaps very recently, meaning it's either going to be very cool due to snow, or slightly cool due to wet ground. There likely isn't any dry ground for quite a distance. Also, there are huge fields there and so the wind is always a fair bit stronger, both at the airport but also in that general area, which on a day like this one seems to have a substantial effect on temps.

Allapattah Flats Wildlife Management Area in western Martin County. A grassy clearing on a raised area with calcareous soil, surrounded by hardwood swamp forest.

A new type of remote weather station I've been working on - a remote temperature/humidity transmitter that mounts to any sort of round column, in either a horizontal or vertical direction. It accepts U-bolts for mounting to tube up to 3" diameter, and hose clamps for up to 21" diameter. This allows it to be mounted to almost any telephone pole, light pole, or tree. It's spaced 3 ft away from the structure to reduce the effects of any heat or moisture it may be emitting.

Just like my other station, this one transmit data via cellular but it's way more portable without the mast and tripod. A pressure sensor and rain gauge could probably be added in the future but I don't have any intention of doing that.

Same type of sensor/radiation shield setup as the other station. Sensirion SHT85 sensor and RM Young shield.

If you wanted a highly exposed coastal station why not go for Jupiter Island. Somewhere around here goo.gl/maps/2iETb9KJyPriiUkM7

How I've been collecting data since May 1st: temperature/humidity using my custom cellular station with the much more accurate sensor and radiation shield, while still retaining the old Ambient PWS for rainfall. Finishing up my new rain gauge soon so that will obsolete shortly though.

I just got back from a little break over to the Isle of Wight & stayed in Shanklin, which is officially the sunniest place in the UK, (that has a Met Office weather station at least), with an annual average of 1976.04hrs Met Office Shanklin Climate Averages 1991-2020

I thought it would be fun to try & find the weather station & located it in a park just outside the town centre.


It's a manual station & has been at this site since 1947 & at another site in the town from 1905.


The only equipment here was the Stevenson screen containing the thermometers & a manual rain gauge, so I had to try & find out where the sunshine was recorded.

Looking online I discovered that since 1948 sunshine has been recorded on the roof of the Shanklin Theatre, so the next day I took a stroll there. It's located in the highest part of the town & I guess at the time must have been the tallest building too.



I didn't think I'd be able to see the sunshine recorder or even where it was located but walking round the side I noticed a flat roofed area at the back of the theatre which had some telecommunications equipment on it, but couldn't see anything else


So then I tried around the other side of the building & spotted the Campbell Stokes sunshine recorder 




Apparently the only access to this roof is from the ladder up the side of the building, so every day since 1948 some poor bugger has had to go up & down to get the readings

I'm thinking the standard sensor height (around 5-7 ft, 1.5-2.1 m, maybe the higher end of the range to get better passive ventilation from breezes, judging by those pics)? Not quite sure how much those homes/bushes would block wind. Just my two cents