Author: Pavan Srinath (page 1 of 5)

Part 2: Why can’t you build a weather station for under $50?

Know Your Climate has embarked on setting up India’s first network of citizen-owned weather stations around the city of Bangalore. Each weather station costs about 35,000 rupees, and a frequently-asked question is why a weather station costs so much. It’s a question that we at Know Your Climate were asking back in 2013.

Rajeev Jha of Yuktix Technologies, KYC’s technology partner, answers. This is the second of a two-part series. [Read Part 1 here.]

In the first part of my explanation of why you cannot build a good automated weather station with $50, I talked of various components which cost more than that. Here I will be elaborating on other reasons that influence the cost of professional-grade devices – the remaining three of seven broad reasons.

At Yuktix, we have to ensure continued supply of weather stations. People can do one-off favours and customisations for cheap, but running production batches repeatedly needs good quality components that are tried, tested and readily available from distributors. This can cost significantly more.

There’s the tyranny of the “MOQ”, the minimum order quantity. If you have budget to make large number of weather stations, say a few thousand, then the whole supply chain will give you deep discounts. Everything from manufacturing to assembly to shipping to testing becomes cheaper per unit. You can afford to get components directly from the supplier instead of using a distributor. Large MOQs also allows you to approach quality vendors who otherwise would never talk to you. Setting up machines take time and no one wants to invest time in you unless you can guarantee good numbers. As a simple example, take fabrication of a metal plate. The vendor with the right machine will never do 10 units. He would like MOQ to be at least a batch in size — which could be a 100 or more units.

Short quantities mean that one has to pay a premium for good components, as well as put up with a high cost of discovery. The only alternative is a compromise on quality.

Sixth, there’s the related cost of a generic design, related to the MOQ challenge.  Managing different ‘Bill of Materials’ (BOM) is difficult for a startup. Getting one design into the market can sap out the funds and you cannot afford to keep going back to drawing board. The next best thing is to do a generic design that you can adapt to different needs in order to make money. However that also means an escalation in costs. As an example we can do a citizen weather station on cheaper PIC18F-type 40-pin chips. However same board will not work for a professional version. Hence we use a 100-pin chip that costs 1600 rupees instead of 150 rupees. The power supply story is similar: if you have the numbers, you can make designs optimised for a solar, battery, or adapter based designs. However doing a generic design that can work with Solar or Li=ion batteries or AC power means more costs again.

Finally, there are labour costs involved in assembly, installation and maintenance of the weather stations. DIY assumes your own labour to be free, and unfortunately we are unable to do that at our fledgling startup.

Rajeev Jha is the founder of Yuktix Technologies, Know Your Climate’s technology partner for the Citizen Weather Network.

Feature photo: Thejesh, the owner of the Electronic City weather station along with his niece and nephew Varsha and Jayanth.

Keep Calm.


Keep Calm and Wait for the Bangalore Rains. Issued in Bangalore’s public interest by Know Your Climate.

Bangalore’s temperature outliers in February 2015

by Pavan Srinath

In the few months that Bangalore does not get much rainfall, temperature is the most interesting (and useful) thing to look at. I take a quick look at how the temperature is varying across the city, thanks to five Citizen Weather Network stations that regularly report data.

Visually representing the data often throws up insights far better than conventional statistical analysis, and the same is true here.

Looking at the past 10 days of weather in Bangalore, it is immediately apparent that most of them follow trends similar to each other. With variation of less than 1°C, at least four out of five stations are quite similar to each other in both maximum and minimum daily temperatures.


Two outliers stand out. For at least the 10 day period in February, Electronics City’s maximum temperature was consistently and significantly lower than the remaining 4 locations in Bangalore. On February 19, Electronics City recorded a maximum of 35.7 °C, a full 2.5 °C higher than all other locations in town.

Coming to minimum temperatures, GKVK, the agricultural univeristy campus north of town, consistently recorded lower temperatures than the rest of the locations. On February 23, the minimum temperature was 13.7 °C, a full 4 °C lower all other areas.

As the Citizen Weather Network grows, we hope to understand the spatial variation in temperature across the city much better. With more data, we may even be able to attribute causes to temperature variation. We will also be able to tell which temperature effects persist through the year, and perhaps quantify heat island effects on the city of Bangalore.

Pavan Srinath is a weather enthusiast at Know Your Climate, and tweets at @zeusisdead.

Temperature data used for the chart can be downloaded here.

In Vijayavani: ಟೆರೆಸ್ ಮೇಲೇ ನೋಡಿ ಸಿಟಿ ಹವಾ

The Citizen Weather Network and Know Your Climate are featured in the Kannada Daily Vijayavani today, by Balachandra Kanyadi.

Read the full article online: ಟೆರೆಸ್ ಮೇಲೇ ನೋಡಿ ಸಿಟಿ ಹವಾ // See the city’s weather on your terrace.


Part 1: Why can’t you build a weather station for under $50?

Know Your Climate has embarked on setting up India’s first network of citizen-owned weather stations around the city of Bangalore. Each weather station costs about 35,000 rupees, and a frequently-asked question is why a weather station costs so much. It’s a question that we at Know Your Climate were asking back in 2013.

Rajeev Jha of Yuktix Technologies, KYC’s technology partner, answers. This is the first of a two-part series. 

You go to an American supermarket and you see a “weather station” that is selling for 50$. If look it up on websites like, you see that are going round for 100$. Even well-known vendors have a kit that will sell for 200$ or 300$. So why the heck we can’t do a station for 50$?

The thinking goes like, get a 8051 chip, plug sensors that are available for 1000/2000Rs and I can have my station for 3000Rs. Sure, you can do that and we have done that. A nice station on breadboard with an LCD in place that could measure temperature, pressure and humidity and display it on LCD. If you add another thousand rupees, you can have the rig beaming data on bluetooth to your phone. Add Wi-Fi and the contraption can be online. So why not?

While working on the Citizen Weather Network, we asked ourselves this question. However, the zeroth questions to settle were, what do we want to do ? What is the end goal? Are we publishing blue-prints for the Hobbyists? Do we want to only demonstrate a proof of concept?

Or instead, do we want a neatly packaged finished product? Where we can provide guarantees on the data, where the data is reliable. Where you don’t need someone near the station at all times who can flip a switch when the station goes down? Where the station cannot be kicked, trampled or spoilt easily.

At Yuktix and at Know Your Climate, we set out to build a research-grade data acquisition platform, that can operate on solar power in remote areas, without the need for human intervention. However, we added a constraint that it should still be affordable and customised for the urban environment.

So here are the first four of six reasons how a Yuktix Automated Weather Station differs from a hobbyist weather unit, and why it costs more.

First,  there is a difference between in-house and out-in-the-wild station. A house oriented station uses your wi-fi or bluetooth, is kept indoors and is not affected by the elements on a daily basis. It is not out in the harsh sunlight and doesn’t have rain pouring on it. That is our first problem. How do we package everything in an all weather proof box? Any quality supplier (with IP65/66/67 certification) will charge you decent money for such a box.

Right now we are paying 25$ for such a weather-proof enclosure. You can surely can pick a cheaper box with gaskets in chuna mandi or Chandani Chowk but the quality is not guaranteed. It is one thing to plug your sensors into your Arduino or RPI where you know the connections and can fix it. It is quite another to put this all back in the wild without any supervision.


The weather-proof box that houses the weather station’s electronics.

Second, there is a cost to data. With a Wi-Fi or Bluetooth attachment, people are using existing internet connectivity, subject to its own failings. We put a GPRS SIM there because we would also like to operate in situations where there is no Wi-Fi nearby (or cannot be). We found that it was better to front-load GPRS data costs for three full years, so that the operational costs of running a weather station are next to nothing.  After all, the value of the weather information increases the longer the data is collected from the same location, year after year. The comparability is obviously superior with long-lived stations. Budget another 75$ for data.

The third factor of cost is a solar radiation shield. You cannot measure air temperature accurately without something to shield the sensors from reflected radiation. Whether it’s from a concrete surface or a whitewashed wall, reflected radiation can dramatically increase temperature and other sensor readings. Instead of measuring ambient air temperature, the sensor can start reading its own heated temperature.

What you need as a ‘radiation shield’ is an enclosure that doesn’t heat up, cuts off all stray sources of radiation (especially around the infrared band) from reaching the sensors, and allows ambient air to keep flowing through. We tried to build our own radiation shield, but one that would not survive the outside environment for long without replacement. A quality product is also one that will not turn yellow in the sun, and you would be surprised at how fast a DIY unit would do that.

The fourth factor of cost is a good rain bucket. The units that measure rainfall and wind in a weather station are typically the only ones that have moving parts, which also means that they are most likely to fail. The rain bucket first. And obviously, no indoor weather station measures rainfall. You need to be able to measure rainfall accurately, but also be able to measure large quantities of it. You want a good funnel that repels water and allows all of it to flow down. And you need to measure the rainfall quantity before the water collected evaporates. We decided to use a high quality tipping bucket weather station which can last a while without rusting or becoming inaccurate in other ways.

Add an extra $200 for both the radiation shield and the rain gauge together.


Radiation shield on the left and the rain bucket on the right in our pilot weather station.

This concludes the first half of why we can’t build a quality automated weather station for $50.

Rajeev Jha is the founder of Yuktix Technologies, Know Your Climate’s technology partner for the Citizen Weather Network.

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