weather forecast with a barometer: feasible? reliable?  - Page 1
Forum section: electronics / general

author: DiTBho
author_rank: Super Contributor
timestamp: March 01, 2023, 01:25:30 pm
content: How good/bad the weather becomes is the result of how great the difference is between the high pressure and low pressure system.high && stable pressure should indicate good weatherfalling pressure should indicate that something is moving in, and you can expect poorer weather...?!? ... something similar - I don't know details, so I suppose - should be used to alert an incoming violent disturbance of the atmosphere with strong winds and usually { rain, thunder, lightning, snow } = (%storm) = ?A barometer, I think even those integrated insideCASIO's Suunto's and Garmin's wrist watches, is a great thing to have because its meaning should help local weather forecast.I know the Suuntu Alpha Core watch implements a "storm alert" function. I don't how its CPU calculate the probability.I'd like to buy some barometer on chip (i2c? SPI? .. mumble), and to write some simple application for the pocket GNU/Linux PDA I have recently integrated into my 90s-titanium bicycle.It would be extremely good for long wild trips, when on Friday afternoon I leave the lake by bicycle with only an ultralight tent, boots and a sleeping bag in my backpack and arrive in the mountains, to proceed on foot and then descend on Sunday morning.I mean, knowing if I'm heading towards a probable storm/pouring rain would be great when I still have time to reverse course(OK, there are commercial Apps for your smartphone, and even commercial wrist smart watches, or even better professional tools used in modern navigation and meteorology ... but ... I'd like to build my-own portable weather forecast machine"because science")Looking for algorithms, tips and tricks.

author: Kleinstein
author_rank: Super Contributor
timestamp: March 01, 2023, 02:14:32 pm
content: It depends a bit on the loacation how good the simple looking at the pressure is. The problem is that the pressure more correlates with the wether right now and less than the next days.Chances are some free web forcast for the next weak is better than what one gets from just looking at the pressure for the next day.For reasonable good short term (next few hours) predictions, when there is a chance for local showers the weather radar is great. Just the pressure would not really help.

author: rstofer
author_rank: Super Contributor
timestamp: March 01, 2023, 03:27:23 pm
content: “Red sky at night, sailor’s delight. Red sky in morning, sailor’s warning”I wonder how well that saying actually works..https://www.loc.gov/everyday-mysteries/meteorology-climatology/item/is-the-old-adage-red-sky-at-night-sailors-delight-red-sky-in-morning-sailors-warning-true-or-is-it-just-an-old-wives-tale/There is some science behind the adage!“With a low and falling glass, soundly sleeps a careless ass; only when ’tis high and rising soundly sleeps the careful wise one.”https://www.sailingtoday.co.uk/cruising/cruising-stories/rain-later-good/

author: tggzzz
author_rank: Super Contributor
timestamp: March 01, 2023, 03:45:43 pm
content: Quote from: DiTBho on March 01, 2023, 01:25:30 pmDefine "good" and "bad" and "location". For example, in the UK high pressure -> hot in summer and cold in winter."%storm"mustincludevariance. With one barometer the variance will be high; with many distrinbuted barometers and temperature stations the variance will be lower. For an idea of the variance, do some research on the reliability of weather forecasts from 1940 to 1960.QuoteFor algorithms, research the fluid dynamics calculations done by the Met Office. Don't expect them to provide a useful answer on a pocket machine.The best tips are:look out the window, upwindlearn how to interpret SLP diagrams such asthis and the others on that sitefor mountains, learn how to interpret skew-t diagrams, and learn how local terrain interacts with the air currents to produce very localised weather conditions that can change very quickly For the reasons, remember your school geography and physics lessons! If you weren't taught them, find an O-level (now GCSE) geography textbook from around 1970.

author: DiTBho
author_rank: Super Contributor
timestamp: March 01, 2023, 04:58:48 pm
content: Quote from: tggzzz on March 01, 2023, 03:45:43 pm... thus, the storm-alarm feature implemented by Suunto, Casio and Garmin in their wristwatches and promoted by their affiliated sports retailers sounds more more "marketing" than scienceI had exactly this doubt the last time I saw their wristwatch in a climbing supply store and was tempted to buy it.It was only 120 Euro instead of 190 Euro for a Suunto Alpha Core with an embedded barometer and thermometer, which CASIO calls "twin sensors", but it's nothing new even with Garmin, since an embedded thermometer is always a problem in a wristwatch unless you to take off your wristwatch and place it somewhere on the ground or on a tree to correctly measure the ambient temperature otherwise it will measures something close to the temperature at your wrist.I'm starting to think that, even using fuzzy logic, the correct slice of pressure can be obtained from a mini cluster of barometers (say, a sensor on your bike's front fork, one on your rear fork, one on your wrist and one on your hat ... are four barometers enough for a local reading? probably ... no, and) depends on the temperature of each reading, and you better have more sensors around you.Ummm, so ... I'm going to re-think, with more radio link capability (wifi 2.4-5Ghz dual band, + hackRF kit and all the GNU/Linux SDR(1) support). This way I can take more serious reading from weather stations around me and the software on my PDA can provide better forecasts.( it won't work)(1) SDR = software defined radio

author: DiTBho
author_rank: Super Contributor
timestamp: March 01, 2023, 05:01:50 pm
content: Quote(Suunto Core Alpha Stealth Watch - Weather Trend Indicator & Storm Alarm)

author: DiTBho
author_rank: Super Contributor
timestamp: March 01, 2023, 05:07:53 pm
content: Just to give you an idea of Km and time I usually run on my bicycle, I can run 160 Km in about 10 hours (with peaks of 45Km/h but only in the plain), not great performance, but 3 hours of warning before a storm are enough to find shelter.So, my specs are weather forecast for the next 3 hours (should be enough)

author: CatalinaWOW
author_rank: Super Contributor
timestamp: March 01, 2023, 05:21:01 pm
content: My commercial weather station has this kind of barometric prediction built in. In my location it is better than flipping a coin by a small margin. For your purposes false positives and false negatives are the critical issues. False positives because of the cost of missing a perfectly fine trip, and false negatives for the obvious reason. Only you can assign the value to these outcomes. A cautious person will not mind the opportunities missed, and deplore miserable or dangerous trips. Adrenaline junkies the opposite.I have personally found the predictions of such low value as to be worthless. Not as good as the ten day out predictions by the national weather service. That is the barometric prediction for tomorrow is not as good as the ten day prediction from nine days ago. But if you are going to be out of communication for more than ten days there might be some value.

author: tggzzz
author_rank: Super Contributor
timestamp: March 01, 2023, 06:16:38 pm
content: Quote from: DiTBho on March 01, 2023, 04:58:48 pmYou do remember these, don't you? Is there any reason to belive those storm alarm algorithms are any better?QuoteWhy is "fuzzy logic" relevant? In what wayisn'tit "magic"?QuoteWith 4 such sensors you would have moredata.Please outline how they would give moreinformation, and what the importance of a "slice of pressure" might be.QuoteYou need to expand the concept of "around you" by over 3 orders of magnitude (or 6 if you are thinking in terms of area).

author: iMo
author_rank: Super Contributor
timestamp: March 01, 2023, 06:31:59 pm
content: High pressure means there is less water vapor in the air (the dry air is heavier), the low pressure means there is more water vapors in the air (the air with a lot of water vapor weights less). It is generally an indicator but not extremely reliable one. The sudden large changes towards the low pressure usually show the wet air is coming at you..

author: TheCalligrapher
author_rank: Regular Contributor
timestamp: March 01, 2023, 06:48:34 pm
content: "The weather is a thing that is beyond me altogether. I never can understand it. The barometer is useless: it is as misleading as the newspaper forecast.There was one hanging up in a hotel at Oxford at which I was staying last spring, and, when I got there, it was pointing to “set fair.” It was simply pouring with rain outside, and had been all day; and I couldn’t quite make matters out. I tapped the barometer, and it jumped up and pointed to “very dry.” The Boots stopped as he was passing, and said he expected it meant to-morrow. I fancied that maybe it was thinking of the week before last, but Boots said, No, he thought not.I tapped it again the next morning, and it went up still higher, and the rain came down faster than ever. On Wednesday I went and hit it again, and the pointer went round towards “set fair,” “very dry,” and “much heat,” until it was stopped by the peg, and couldn’t go any further. It tried its best, but the instrument was built so that it couldn’t prophesy fine weather any harder than it did without breaking itself. It evidently wanted to go on, and prognosticate drought, and water famine, and sunstroke, and simooms, and such things, but the peg prevented it, and it had to be content with pointing to the mere commonplace “very dry.”Jerome K. Jerome "Three Men in a Boat"

author: james_s
author_rank: Super Contributor
timestamp: March 01, 2023, 06:57:00 pm
content: Do you have a smartphone? The weather app on mine provides a far more detailed and accurate forecast than a barometer. Certainly a barometer can provide valuable information, but meteorology is a complex topic and there is much more to predicting the weather than watching the pressure.

author: IanB
author_rank: Super Contributor
timestamp: March 01, 2023, 07:01:57 pm
content: Quote from: imo on March 01, 2023, 06:31:59 pmI'm not in any way a meteorologist, but isn't there more to it than that? High pressure usually indicates a stationary, stable air mass, while low pressure usually indicates winds and swirling air masses that are usually associated with storms?

author: iMo
author_rank: Super Contributor
timestamp: March 01, 2023, 07:10:28 pm
content: You may have stable weather with both high and low pressures. The changes make the storms and windy weather (and usually the abrupt changes from high to low, like from 1035hPa to 910hPa within 1 hour - that would indicate large water masses in the clouds or fog are approaching you, and that generates storms, rain and the pressure front the strong winds).

author: tggzzz
author_rank: Super Contributor
timestamp: March 01, 2023, 07:35:27 pm
content: Quote from: imo on March 01, 2023, 06:31:59 pmEr. No. The statements in your first sentence are not even wrong.High pressure is caused when air masses descend. Low pressure is the reverse.Bonus questions: how much does a fully developed cumulo nimbus cloud weigh? What is the humidity inside the cloud?

author: iMo
author_rank: Super Contributor
timestamp: March 01, 2023, 07:42:21 pm
content: Quote from: tggzzz on March 01, 2023, 07:35:27 pmI doubt it is related to the movement of the air masses. It is simply because the dry air is heavier..

author: DiTBho
author_rank: Super Contributor
timestamp: March 01, 2023, 07:42:43 pm
content: Quote from: tggzzz on March 01, 2023, 06:16:38 pmSome algorithms are entrusted with drawing inferences from the data.{ barometer, thermometer } reading -> { stormy, rainy, change, fair, very dry }AI-based algorithms are very good at this, but consume too much power, and my little PDA is a little battery powered ARM@400Mhz with only 64Mbyte of ram.I hacked the battery, tripled its capacity (from old NiHm to modern LiPo), installed a modern GPS module; now I have about 40 hours of battery life with a new frequency scaling kernel hack that forces CPU @ 50Mhz, the wifi completely off and screen back-lit at 0% of la its brightness when not in use and 40% when you need to take a quick look.Not bad for a survival travel computer! And I'm working on my front wheel (700x24,2U) to install a hub dynamo capable of generating up to 6-Watt so that I can charge the PDA battery while pedaling.Fuzzy-logic consume less resources, it's not as great as AI-based (tensor-flow) algorithms, but if well-done and well-tuned it is less sensitive to small variations in values than every direct approach, and if well integrated with statistics, it allows discrete inferences.Hence, even if it's a sub-sub-optimal approach, it should be more robust in classifying discrete events from noisy data-set from digital barometers (which are very noisy).(d'oh, the ARM chip is an intel PXA, there is no FPU ... no DSP ... kernel and userspace emulation)

author: tggzzz
author_rank: Super Contributor
timestamp: March 01, 2023, 07:52:28 pm
content: Quote from: imo on March 01, 2023, 07:42:21 pmBonus questions: how much does a fully developed cumulo nimbus cloud weigh? What is the humidity inside the cloud? What is the humidity immediately outside the cloud?

author: floobydust
author_rank: Super Contributor
timestamp: March 01, 2023, 08:09:57 pm
content: OP it's very limited by looking at one variable only. I watch barometric pressure and the changes can tell you when a system is moving in/out, but not what effect it will have. We had a recent large jump up/down in two days from 100 to 104kPa (graph) as a cold front moved in and down to -30°C and then back up to 0°C. Will it snow? Stare at the graph and it's too difficult. You need a few long-term averages and compare to the trend. I find you can forecast a weather change only when there are extreme excursions in barometric pressure, over X hours.For a long time, weather forecasting based on a barometer was life/death for a seamen. Despite the finest brass and oak, the gauges were not enough.Royal Navy Admiral FitzRoyStorm_glass(he did barometers too) atLee Valleydiscontinued.I did try theKikkerland Storm Glassbut it did nothing, so I did the gentle reheat and recrystallize and... it did nothing. The formula/Camphor or construction might be wrong nowadays. It is using both temperature and pressure.Tempest_prognosticator or leech barometerprobably more accurate than some meteorologists lol.

author: golden_labels
author_rank: Super Contributor
timestamp: March 02, 2023, 12:05:47 am
content: With enormous amount of global data and detailed models we have now, predicting weather events for a few days ahead is unreliable. In large urbanized areas it can hardly reach a few hours, still with huge uncertainity: predictions are breaking due to air currents and very fine scale required to model them. Sunny weather is generally easy to predict, but anything related to clouds, thunderstorms or strong winds… nope.That should give you the upper bound, of what you may expect from a barometer. A barometer, that gives you single value from a single point on Earth.My guess,unsupported by evidence, is: if you were a farmer and had no access to better information, waking up in the morning, looking and the barometer and expecting either rain or fine weather was still very valuable even if it failed 3/4 of times.But nowadays your national weather instututions are likely publishing forecasts from their models, with 10 km and 15 min resolution, very reliable for 24h and still pretty good for 48h. Outside cities, that is.Unfortunately Google Scholar does not yield any interesting results. I suspect that’s because barometer use started to drop, replaced with national scale forecasts, before methods permitting testing their effectiveness became widely known and used in science (second half of 20th century).

author: SiliconWizard
author_rank: Super Contributor
timestamp: March 02, 2023, 05:56:57 am
content: Well sure, we were using barometers along with others cues to predict weather for centuries before computers and more elaborate models appeared.Now you need to define what "forecasting" means to you.What you can predict with just atmospheric pressure and its changes is limited. Sure a relatively fast drop in pressure is usually not a good sign. But you don't know what's really going to happen. Some heavy wind, or rain, or a storm, or... a combination thereof. A slow drop may not mean really bad weather OTOH. It's probably going to be cloudy, but you can go with a low pressure for days on end without a drop of rain.

author: tggzzz
author_rank: Super Contributor
timestamp: March 02, 2023, 08:38:33 am
content: Quote from: golden_labels on March 02, 2023, 12:05:47 amIn the UK the rule of thumb is that tomorrow's weather will be like today's weather. That is probably 50% correct.A barometer will increase that slightly.Looking upwind will increase it more.In hilly areas, the predictability is worse.Nowhere is the predictability sufficient for the OP's requirements. That's why weather (cf climate) is a traditional conversation topic.

author: RoGeorge
author_rank: Super Contributor
timestamp: March 02, 2023, 08:53:27 am
content: TI has had a wrist watch with a MSP430 as a devboard.https://www.eevblog.com/forum/microcontrollers/msp430-wrist-watch-project/It's programmable, has an atmospheric pressure sensor and a low power RF link with its own USB dongle for PC. The pressure sensor is used there as an altimeter, but should be possible to use it for weather forecast if you tinker a little with the code.

author: DiTBho
author_rank: Super Contributor
timestamp: March 02, 2023, 09:45:58 am
content: Quote from: RoGeorge on March 02, 2023, 08:53:27 amso, let's go with triplex { barometer, thermometer, altimeter }.I can integrate all of these sensors inside my Japanese PDA

author: tggzzz
author_rank: Super Contributor
timestamp: March 02, 2023, 10:11:41 am
content: Quote from: DiTBho on March 02, 2023, 09:45:58 amA humidity meter would be more useful. I doubt the results would be much use for you, and certainly less useful that a decent online forecast - or even using your eyes.

author: DiTBho
author_rank: Super Contributor
timestamp: March 02, 2023, 10:17:30 am
content: Quote from: SiliconWizard on March 02, 2023, 05:56:57 amI think three hours of warning before a storm/rain is *ok* and enough to find shelter. I don't need precise forecast, only the weather forecast for the next three hours in terms of { find a shelter, continue }weather forecast: func(barometer, altimeter, thermometer) -> mission { find a shelter, continue }find a shelter(wait for the end of the storm, *) -> mission { go back home, continue }*: unexpected, local eval on the environmental data of the moment

author: DiTBho
author_rank: Super Contributor
timestamp: March 02, 2023, 10:28:37 am
content: Quote from: tggzzz on March 02, 2023, 10:11:41 amonline forecast = internet?There are areas where WiFi is not good and areas where you don't have WiFi coverage. Forget smartphones there, unless you use a Sat Garmin bridge. I don't own one. This is also the reason why I would like to bring with me an SDR engine (software defined radio): if you don't have WiFi coverage and mobile phone, well, your smartphone is useless, but the SDR could still capture a radio (even AM, FM, etc) signal for your PDA.I don't want to bring my smartphone with me, however. I don't need to publish photos on social media and in case I have a small camera reflected in my backpack-I need to think about the humidity meter.

author: jpanhalt
author_rank: Super Contributor
timestamp: March 02, 2023, 11:35:19 am
content: Quote from: DiTBho on March 02, 2023, 10:28:37 amThe British Met Office broadcasts weather reports (https://www.gov.uk/government/organisations/met-office#:~:text=The%20Met%20Office%20is%20the,%2C%20industry%2C%20agriculture%20and%20commerce.) I have not listened to them.The equivalent US service is NOAA . It broadcasts regularly on special frequencies. I my area, which is remote, I have an inexpensive, battery operated "NOAA" radio. Our internet and electricity go down regularly with severe storms.As for a barometer, it can be useful and is certainly more useful than humidity in my opinion. I've only visited the UK once, which was for a week. As I recall, the island was divided vertically. On one side it was rain and fog and the other was fog and rain. The weather forecast basically told you which side you were on. (We did arrive on a sunny day and drove South around Salisbury, saw the Magna Carta, then to a small coastal town -- very nice town and tea room -- before going north to Bristol to spend a couple of days before returning to London. Great visit, the weather was unimpressive compared to the violence we see in our Midwest.)

author: james_s
author_rank: Super Contributor
timestamp: March 02, 2023, 07:05:20 pm
content: I visited the UK in late September 2011 and it was beautiful unusually warm sunny weather throughout most of the trip. Then on the last day it shifted to dark and gloomy with gusty winds and pissing down rain. I was told that was more typical of the season.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: March 02, 2023, 07:39:11 pm
content: I don't want to take away from your project if you are getting joy from it. But you have access to the internet since you are on this forum, so you have access to the national weather services. If you use those well to plan your ride you will be far better off. You can even modify your route to get better wind conditions. I know. I do it.You just get the local forecasts for a few well spaced locations in your route. Do it the night before, or even better, in the morning before you depart. Here in the US they are update roughly every six hours and are really quite good for the next 24 hours, often predicting the arrival of windy conditions within 15-30 minutes.

author: tggzzz
author_rank: Super Contributor
timestamp: March 02, 2023, 07:59:46 pm
content: Quote from: james_s on March 02, 2023, 07:05:20 pm"Season" implies climate.The UK, because of the track of the jet stream, doesn't have climate. We have weather.One turning point in the south and midlands has traditionally been Guy Fawkes' night, because that's around the time when we start wearing clothes for cold damp weather. Over the past decade or so, that's been less true

author: DiTBho
author_rank: Super Contributor
timestamp: March 02, 2023, 08:50:36 pm
content: Quote from: CatalinaWOW on March 02, 2023, 07:39:11 pmWrong assumptionAt the moment I'm not in the mountains, I'm in an urban area where the WiFi level is great. Friday afternoon, after work, I will take the car to reach another location on the outskirts, in open countryside, then the bicycle to reach the final destination in the mountains, and - already tested - there will be areas not covered by WiFi.

author: james_s
author_rank: Super Contributor
timestamp: March 03, 2023, 12:09:10 am
content: Is weather radio a thing there? Here we have NOAA weather stations that broadcast weather updates continuously on VHF, from my house I can pick up KHB60 on 162.550 MHz, there are a bunch of them in other locations.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: March 03, 2023, 02:13:15 am
content: Quote from: DiTBho on March 02, 2023, 08:50:36 pmActually correct assumption. The weather reports you collect before you leave on Friday will give you better data through the weekend than a barometer/thermometer setup. If you are going on a two week holiday it would probably be worth a trip into internet land once or twice.

author: SiliconWizard
author_rank: Super Contributor
timestamp: March 03, 2023, 02:38:15 am
content: Quote from: DiTBho on March 02, 2023, 10:17:30 amFor three hours of warning, if you have minimal experience with mountain weather, it should not be hard to predict just looking at the sky and other cues such as wind.Yeah, that's how people did it for a very long time.

author: james_s
author_rank: Super Contributor
timestamp: March 03, 2023, 08:31:15 am
content: Mountain weather is notoriously unpredictable even with state of the art equipment, weather balloons, supercomputer simulations, etc. I live in a mountainous region and the forecast has always been a bit of a joke, if you check the 7 day forecast and then check it again 5 minutes later it is not uncommon for it to be different. When you're actually up in the mountains themselves the weather can change very rapidly, I've been on hikes where it changed from clear and sunny to cold and windy with pissing down rain, over just a matter of minutes.

author: DiTBho
author_rank: Super Contributor
timestamp: March 03, 2023, 09:14:22 am
content: ok, I have collected enough information to proceed alone with my project.

author: tggzzz
author_rank: Super Contributor
timestamp: March 03, 2023, 10:31:51 am
content: Quote from: DiTBho on March 03, 2023, 09:14:22 amBefore relying on it, you would be wise to spend several months validating its predictions against what actually happens. But you know that.In mountains, as others have noted, weather varies significantly, unpredictably, and very locally - e.g. raining on one side of the hill but not the other. Local advice can be very useful

author: DiTBho
author_rank: Super Contributor
timestamp: March 03, 2023, 11:05:23 am
content: Quote from: tggzzz on March 03, 2023, 10:31:51 amyup, that's the point: I need on field experiments

author: SiliconWizard
author_rank: Super Contributor
timestamp: March 03, 2023, 07:49:16 pm
content: Note that specifically detecting a coming storm can be done using a dedicated type of sensor - and I guess the real danger is a thunderstorm, rain is just water.There are professional and very expensive detectors for that, but an affordable, "hobbyist"-level one is the AS3935, for which you can find relatively inexpensive breakout boards:https://www.sparkfun.com/products/15441Combining this with a barometer sensor and humidity sensor may get you something helpful after some field experimentation.If anything, it should be fun.

author: CatalinaWOW
author_rank: Super Contributor
timestamp: March 03, 2023, 08:25:15 pm
content: Quote from: DiTBho on March 03, 2023, 11:05:23 amThe field experiments are fun, but you can get far more data by matching your algorithm against historical data. Try multiple locations in your area of interest. With a bit of poking a lot of this data is available.Try the Weather Underground, Ambient Weather, the national weather agencies and TV stations for starters.

author: floobydust
author_rank: Super Contributor
timestamp: March 03, 2023, 09:09:37 pm
content: Quote from: SiliconWizard on March 03, 2023, 07:49:16 pmFranklin Lightning Sensor ICAS3935is a FAIL. Many issues but ultimately it false triggers on AM radio. It's tuned to 500kHz. People had problems with them. It did win many awards lol.Here's your weather forecast lolhttps://earth.nullschool.net/#current/wind/isobaric/500hPa/overlay=temp/orthographic=-80,27,424