Relative humidity
How close the air is to saturation. High RH marks moist layers and the likely height of cloud.
Wx Labs · Weather UAS
WxUAS-0002 is flying repeated vertical soundings at the Pallas Cloud Experiment in Finnish Lapland. Each colour strip is one ascent through the lower troposphere — the layer where fog, low cloud, and most of the weather that affects people actually form. Shown here: the latest observation day.
Weather is three-dimensional. Most of what we measure every day is not.
A conventional surface station tells you the temperature, humidity and wind at one height. A radiosonde can give a full vertical profile — but only from a handful of stations, typically twice a day. Between those launches, the atmosphere can change completely: a nocturnal inversion can form and break, a cloud deck can lift or collapse, and the boundary layer can grow by a kilometre.
That lowest one to two kilometres is where we live. It is also the hardest layer for satellites to see clearly, and the one numerical weather prediction models most need help with. Weather drones close the gap. They can be launched on demand, many times a day, and return a thermodynamic profile with the vertical detail of a radiosonde and the cadence of a field campaign.
Wx Labs builds observing systems that turn recent atmospheric science into practical measurements. WxUAS-0002 carries a meteorological payload on a small uncrewed aircraft. The result is a repeatable sounding of the lower troposphere: temperature, humidity, pressure and derived quantities such as mixing ratio, potential temperature and lapse rate, from the surface up through the boundary layer and into the free troposphere above.
Those profiles are useful to forecasters watching fog and low cloud, to researchers studying Arctic mixed-phase cloud, and to anyone who needs to know how the atmosphere is layered now, not twelve hours ago.
PaCE is a multi-institute field campaign at the Pallas Atmosphere–Ecosystem Supersite in Finnish Lapland, about 170 km north of the Arctic Circle.
In autumn the hilltop station at Sammaltunturi sits in cloud for much of the time. That makes Pallas an unusual natural laboratory: you can measure cloud from the inside on the ground, while aircraft, drones and remote sensors profile the same air from the valley floor up through the cloud layer. Earlier PaCE intensive periods brought together aerosol, cloud-microphysics and meteorological measurements from surface sites, tethered balloons and uncrewed aircraft.
PaCE 2026 continues that work. Wx Labs is contributing frequent thermodynamic profiles with WxUAS-0002, flown from the valley near Kenttärova (67.997°N, 24.210°E, about 270 m above sea level). The flights shown here reach about 8000 ft (2.4 km) above sea level — high enough to sample the boundary layer, the cloud-bearing layer, and the drier air above.
The scientific aim is simple to state and hard to do well: observe how temperature, moisture and stability evolve through a subarctic day, at a site where low cloud, inversions and aerosol–cloud interaction are the everyday weather, not the exception. Repeated drone soundings give a height–time picture that a single radiosonde cannot.
The profiles follow the World Meteorological Organization conventions for uncrewed soundings, so they can sit alongside other weather-UAS data in a common format. The NetCDF files below use that layout.
Switch variable and hover a strip to read the value, the launch slot and the height. Each column is one 30-minute window; colour is the 12 m mean along that ascent.
How close the air is to saturation. High RH marks moist layers and the likely height of cloud.
In situ temperature on the ascent. Cooler colours are colder air; warmer colours are milder.
How temperature changes with height. Red is more unstable than −6 K km⁻¹; white is that reference; blue is more stable, including inversions.
The mass of water vapour per mass of dry air. Unlike RH, it does not depend on temperature, so it traces moist and dry air masses cleanly.
The temperature a parcel would have if brought dry-adiabatically to 1000 hPa. It increases with height in a stable atmosphere and highlights layered structure.
Temperature minus dew point. Blue is a small depression — air close to saturation. Yellow is drier air.
The same fields, drawn as publication figures for the selected day. Open an image for the full-resolution plot.
The same fields across every flying day, including the quiet hours between. Open an image for the full-resolution plot.
The plots are not raw flight tracks. They are a consistent height–time analysis of the ascents, so days can be compared side by side.
A profile starts when the aircraft is climbing at 0.5 m s⁻¹ or more. Short pauses of less than 20 s are kept as one flight. Only climbs of at least 50 m are retained, so brief hops do not enter the record.
Pressure, temperature and humidity are recorded at 1 Hz on the WxUAS payload and merged with the aircraft’s position to give a single thermodynamic profile for each ascent.
Each ascent is placed in a 30-minute slot from its start time, so a launch at 07:04 UTC appears in the 07:00–07:30 column. If two profiles fall in the same slot, the taller one is drawn.
Values are averaged in 12 m layers above sea level, so a typical 6 m s⁻¹ climb contributes about two 1 Hz samples to each bin. The viewer and figures show the profile from the surface up to 8000 ft (2438 m) AMSL, covering the boundary layer and the lower free troposphere at this site.
Each ascent is published as NetCDF, following the World Meteorological Organization conventions for uncrewed aircraft soundings.
The files use the Climate and Forecast (CF) metadata conventions and the WMO UAS Demonstration Campaign (UAS-DC) profile layout, including FM 303-2024 variable names. That is the interchange format WMO developed so weather-drone soundings from different operators can be compared, archived and read by the same tools. Temperature, humidity, pressure, winds and derived moisture variables are included for each ascent.
Wx Labs follows those conventions. The UAS-DC is described on the WMO Uncrewed Aircraft Systems Demonstration Campaign page. The scientific case is set out in the WMO white paper Global Demonstration Campaign for Evaluating the Use of Uncrewed Aircraft Systems in Operational Meteorology (WMO-No. 1318, 2023), by Debbie O’Sullivan, James O. Pinto, Ben S. Pickering and Dean Lockett — read the white paper.
| Slot | Ascent start | Max height | NetCDF |
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