Weather Station Ideas

[Gina]

Ordered another ESP32 module.  So much easier to deal with the exact same device for the different weather station sensors.  I shall probably be ordering more as I can see other uses for them.

[jiberjaber]

Mine works on a scheduled reading and uses a rolling average for most measurements.  Not sure I'd rely on the web request to trigger measurements, some sensors require some integration time for them to yield a result.

[Gina]

I might go on to add code to store data and make tables generated from logged data.  I think graphs might be pushing it.  I shall need to look into how much data I could store within the ESP32.  I too think it would be better to schedule data acquisition and store it, then let the web access code read the stored data rather than actually take it.  That is the way I have always done things.  You have to do this for wind and rain measurements anyway.

[Gina]

I may install the ESP32 with BME280 and DHT22 in/on the observatory tomorrow.  I'll design and 3D print a tiny Stevenson screen for the outside sensors and mount the scope room sensor just inside on the other side of the north wall.  I think I'll put the BME28- outside in the Stevenson screen as the air pressure may be affected in the obsy by wind blowing through it.

[wimvb]

3 hours ago, Gina said:

Ordered another ESP32 module.  So much easier to deal with the exact same device for the different weather station sensors.  I shall probably be ordering more as I can see other uses for them.

They are quite handy to have around. I think I have about six of them now: SQM meter, mini weather station, ordinary weather station (still fighting to get the RS485 interface working), and a few more for testing stuff. But I rarely use them with the Arduino IDE. I use the Thonny micropython editor most of the time.

https://thonny.org/

[Gina]

What do you find better about the Thonny micropython editor?

[wimvb]

Nothing really. I wanted to learn python. An added bonus was that I skip pressing that button on the esp every time I want to upload a new program version.

[Gina]

Having looked into where I would like to put the temperature and humidity sensors in the scope room and outside I'm thinking it may be worth using separate ESP32s.  After all they don't cost much and I don't know how far from the ESP32 I can have the DHT22.  The scope room sensor could then be on the pier giving more accurate data on imaging conditions.

[jiberjaber]

22 minutes ago, Gina said:

Having looked into where I would like to put the temperature and humidity sensors in the scope room and outside I'm thinking it may be worth using separate ESP32s.  After all they don't cost much and I don't know how far from the ESP32 I can have the DHT22.  The scope room sensor could then be on the pier giving more accurate data on imaging conditions.

My DHT22 on my dew controller is on about 2m of cable.  You will need some integration time for the DHT22 plus they are not as robust as some of the other sensors (SHT30 for example) however the SHT30 is I2C so remote mounting slightly complicated.

[Gina]

I've designed the Stevenson screen.  It'll take a while to print!  It is in one piece except I may put a bottom on it.  That was on at first until I realised I couldn't get the electronics into it!  🤣

[Gina]

Can I have opinions please.  Is the north wall of the observatory the best place for a Stevenson screen for the outside measurements of temperature, humidity and pressure?  Would I get sufficient airflow it?  Or would it be better on a post away from the building?

[jiberjaber]

11 minutes ago, Gina said:

Can I have opinions please.  Is the north wall of the observatory the best place for a Stevenson screen for the outside measurements of temperature, humidity and pressure?  Would I get sufficient airflow it?  Or would it be better on a post away from the building?

Mines on a side that faces NE - I'm not after super accuracy, just representative of local conditions.  

My first screen was similar but pre-3d printer so consisted of a lot of plant saucers, spacers and long bolts  

 

[Gina]

Have the ESP32 with BME280 in the scope room near the pier.  Working fine.

[Gina]

Well it was but now I've lost connection.  Hope this doesn't mean the WiFi is unreliable.  I'll pop out shortly and see if I can see any reason.

[wimvb]

Probably the same issue I have, the connections aren’t closed properly. I read about a fix somewhere. I’ll see if I can find it.

[Gina]

Found the problem - bad connection.  WiFi working again but now have a bad connection to the BME280.  Just using jumper wires and they aren't very tight.  I'll build it on a stripboard shortly.

Later...  Working again now.

Edited July 29, 2020 by Gina

[wimvb]

Have a look here as well, even if it's just for future reference

https://rntlab.com/question/solved-esp32-web-server-drops-connection-crashes/

 

[Gina]

Have you any comments about the location of the Stevenson screen Wim?

[wimvb]

1 hour ago, Gina said:

Have you any comments about the location of the Stevenson screen Wim?

Unless you want to do science with it, I think the exact location isn't critical. With the type you have, on a pole would seem the obvious place. If it were a box type enclosure made of wood, I would place it on a wall in an exposed location, so it would get good air circulation. From which direction does the wind blow? Even though you don't measure wind speed and direction from it, make it exposed enough, and not too sheltered. Near a south wall is of course definitely a no go.

Btw, I found why at least my weather station becomes unresponsive after a while. The socket methods that I use, are blocking. I added timeout routines and got it working. I will put the fix in my weather station thread.

https://stargazerslounge.com/topic/338749-yaaws-yet-another-arduino-weather-station/?do=findComment&comment=3918727

[Gina]

The prevailing wind is SW.  The observatory is about 15° off east-west, in a clockwise direction viewed from above.  The wind sensors are on the SW corner in this photo.  The long wall with the ASC pole attached is where I was thinking of putting the Stevenson screen.  Met Office suggest a height of 4ft (1.2m) but pics of lots of weather stations show it at all sorts of heights.  Maybe it doesn't make much difference

[Gina]

Seems the "easy" places to put the Stevenson screen would not be good!

The north obsy wall, while shaded from the sun would not allow much airflow.  On the wind sensor pole would suffer from heat from the black rubber roof of the obsy.  Same with the ASC pole.

Here's a rough aerial view courtesy Google (a few years old).  The rough ground cover and the whole of the area is currently overgrown with thistles but will be cleared.  I'm thinking perhaps on a fence post on the boundary where I took a tree down might be as good as anywhere (if within WiFi range).  The greener area is my property - the not so green area is my neighbours field.

Edited July 30, 2020 by Gina

[Gina]

In parallel with thinking about sensor locations I'm looking into the coding.

The trend in atmospheric pressure would be a useful extra and quite easy to do.  Maybe max and min temperature but there would be a need to reset it.

For the wind instruments, instantaneous wind speed has little meaning.  I'll probably average over 5 minutes.  Data for mean speed and gust would be useful.  The wind direction is rather more complicated.  Firstly the read switch on/off reading has to be converted to one of sixteen.  Then this would be smoothed with Consensus Averaging.  It would be nice to generate a Rose Chart but that will have to be for the future.

Edited July 30, 2020 by Gina

[JamesF]

I wouldn't personally have a problem with where you intended to site the screen on the wall of the observatory, Gina.  As long as there's fairly free movement of air around it I think that should be fine for the sorts of stuff we want them for.  Mine is fixed to the NE wall of the observatory with a couple of battens between the screen and the wall to allow air to pass between the two (the wall is insulated too, so there shouldn't be much heat coming from the inside either).  The idea is not to allow the wind to rip through the inside of the screen after all, merely to allow a free exchange of air between the inside and the outside, and to ensure that the air outside is reasonably representative of the area generally.

Fix a bit of 2x2 to the wall and screw the screen to that and I reckon you'll be absolutely fine.

James

[Gina]

Looking at the wind vane calculations...  I will have 8 digital inputs to the ESP32 two of which may be on at the same time.  A "sledgehammer" approach would be to assign values of 1, 2, 4, 8, 16 etc. and then use a look-up table to convert to 16 values 0-15. This table would have 256 entries.  I'm wondering if this would put a strain on the ESP32.  Guess I can try it and see.  Then Consensus Averaging with magnum maths and put the result in the HTML string.

[JamesF]

19 minutes ago, Gina said:

The trend in atmospheric pressure would be a useful extra and quite easy to do.  Maybe max and min temperature but there would be a need to reset it.

For the wind instruments, instantaneous wind speed has little meaning.  I'll probably average over 5 minutes.  Data for mean speed and gust would be useful.  The wind direction is rather more complicated.  Firstly the read switch on/off reading has to be converted to one of sixteen.  Then this would be smoothed with Consensus Averaging.  It would be nice to generate a Rose Chart but that will have to be for the future.

The code I'm running at the moment for mine, which is just a little bit of Perl I knocked up, keeps min and max temperatures since midnight, but also a minimum overnight temperature (where "night" is between 6pm and 6am).  Wind speed I average over a minute, but for wind gust I take readings around three seconds apart whenever the code isn't doing anything else, and calculate the gust speed from that.  I have to admit that it hadn't occurred to me to check if there is some standard for the length of a "gust".

James