ETH Zurich’s Researchers Are Flying Meteomatics’ Weather Drones Into the Clouds

Clouds are one of the main elements that regulate Earth’s climate. Understanding cloud microphysics is thus paramount to more precise climate projections. In this story, we explain how ETH Zurich’s researchers are using Meteomatics’ Weather Drones – the so-called “Meteodrones” – to conduct cloud seeding experiments to study cloud-aerosol interactions and precipitation events.

How Clouds Relate to Climate Change

Understanding clouds is essential to a comprehensive understanding of the planet’s climate as they directly regulate the water cycle and the temperature on Earth. While some types of clouds will trap heat by reflecting energy back to the surface, others will reflect sunlight, cooling the surface. As they determine precipitation and sunlight, clouds impact many industries, in particular those dependent on a balanced amount of water and sunlight, such as agriculture and renewable energies.

Therefore, understanding cloud formation and evolution is highly important not only for better forecasting in the short term, but also in the long run, especially in a changing climate.

In fact, clouds and cloud-aerosol interactions represent major sources of uncertainties in climate projections.

For example, how will clouds change in a warming climate? What is the influence of clouds on the Earth’s radiation budget? Answering these questions will help protect several industries and the quality of life of many people in the future.

As one of the top universities in the world, the Swiss Federal Institute of Technology in Zurich – ETH Zurich – heavily supports scientists involved in climate research.

In the Institute for Atmospheric and Climate Science, Professor Ulrike Lohmann leads the Atmospheric Physics group which aims to improve our ability to predict weather and climate by studying the formation and evolution of clouds, especially cloud-aerosol interactions.

One of the group’s projects is CLOUDLAB, dedicated to improving the understanding of cloud microphysical processes and precipitation formation to better simulate and predict precipitation events.

The team performs cloud seeding experiments in wintertime stratus clouds to study ice crystal formation and growth leading to precipitation, with a multi-dimensional set of observations and numerical modeling.

Cloud Seeding With Drones From Meteomatics

Anna Miller, Doctoral Student and CLOUDLAB team member, explained how the data collection process in the Atmopsheric Physics group evolved over the years, in terms of flexibility to measure cloud particles, wind, and aerosol concentration.

They started with ground-based measurements of unperturbed clouds (i.e., clouds that were not modified by human activity) at the mountain top observatory, but these measurements were highly influenced by the ground and blowing snow.

Then, the team moved towards measurements on a cable car, which reduced the influence from the ground and gave some vertical structure, and then on tethered balloons, with more vertical structure and more possibilities of locations to measure.

Finally, they adopted Meteomatics’ Weather Drones. With our Meteodrones, the research could take a decisive step forward.

The drones allowed for more flexible measurement paths using integrated atmospheric measurement sensors.

But most importantly, they offered the team a way to perform targeted cloud seeding experiments.

As Dr. Lukas Hammerschmidt, Meteomatics’ Chief Drone Officer, says, “Our Meteodrone is the only drone in the world that could even be considered to do cloud seeding”.

That’s because as our Meteodrones fly up to 6km, they were engineered to resist very low temperatures and high wind speeds. Thanks to our propeller heating system, Meteodrones can fly into supercooled clouds without the rotor blades icing. This is essential for a successful cloud seeding process, because the seeding can only work in clouds with temperatures less than -5 °C.

With the drone, the scientists can control exactly where to inject the particles into the cloud and directly measure the downstream ice crystals to infer ice crystal growth rates with a tethered balloon.

According to Miller, “targeted cloud seeding with the help of a drone allows us to alter cloud conditions in a known and specific way, for us to then observe the related microphysical changes with an extensive set of instrumentation. This is different to only observing and measuring unperturbed clouds. Specifically, measuring ice crystal growth in a cloud is made possible when we can first intentionally create ice crystals.”

Meteomatics Created a Bespoke Solution for CLOUDLAB

CLOUDLAB’s specific flight missions needed a bespoke solution. The team asked us for two MM-670 ML Meteodrones that should be adapted to their particular needs. And that’s what our engineers did.

The first drone (a) was equipped with flares that burn in-flight for cloud seeding. The second (b), with an optical particle counter for measuring aerosol particles in-flight.

As Miller explains, the two Meteodrones are an essential part of their research in CLOUDLAB:

“We use the seeding drone for experiments in- and out-of-cloud. For these experiments, the drone flies to a certain height and the attached flares are ignited, releasing silver iodide particles into the air. When it’s in-cloud, we monitor the related microphysical changes using several cloud radars and our tethered balloon system. We burn the flares also out-of-cloud, so that we can see the aerosol plume to measure and characterize the dispersion of the plume with our second drone, the measurement drone (or POPS drone, because POPS is the optical particle counter we use on it). We also use the POPS drone to do vertical profiles, for measuring temperature, humidity, wind, and aerosol concentration. This helps us determine the current atmospheric conditions, which inform the experiments.”

Not only the hardware was adapted, but also the software. Our drone software development team adjusted the user interface to make it easier for the CLOUDLAB team to configure their flight missions and integrated a chart to display the particle counts and distributions.

In addition to the drones, CLOUDLAB’s team received a full-day of training to operate the drone, which included flying practice, air space regulations, and the pre-flight checklists to ensure that they could operate the drones safely. We’re regularly in touch with them to keep improving the systems to their new missions and providing on-call assistance and maintenance of the drones.

From Scientists to Scientists

In search for more knowledge about clouds and precipitation events, ETH’s researchers are flying Meteomatics’ Weather Drones into the clouds. Equipped with burning flares and an optical particle counter, our drones are allowing them to conduct cloud seeding experiments and study cloud-aerosol interactions.

As a company made of climate scientists and engineers, many of whom had academic careers – including a number of ETH graduates – we feel especially connected to this project.

Ultimately, we’re driven by the same ambition: to understand weather.

We’re thus happy to collaborate with CLOUDLAB’s team to improve the understanding of cloud microphysics, leading to enhanced precipitation forecasting that will help us face the challenges of a warming climate.

To learn more about our weather drones, click on the link below.