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$. If look it up on websites like Alibaba.com, you see that are going round for 100$. 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.

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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.

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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.

1 Comment

  1. Which temperature humidity sensor do you use in this weather station box? What is its accuracy? Can you give some information about that?

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