A high-resolution infrared hygrometer (FIRH) was adapted to measure humidity and its rapid fluctuations in turbulence inside a moist-air wind tunnel LACIS-T where two air streams of different temperature and humidity are mixed. The measurement was achieved from outside the tunnel through its glass windows and provided an agreement with a reference dew-point hygrometer placed inside. The characterization of humidity complements previous investigations of velocity and temperature fields.

Dual thermistor radiosonde (DTR) comprising two (white and black) sensors with different emissivities was developed to correct the effects of solar radiation on temperature sensors based on in situ radiation measurements. All components contributing to the uncertainty of the radiation measurement and correction are analysed. The DTR methodology improves the accuracy of temperature measurement in the upper air within the framework of the traceability to the International System of Units.

The measurement of temperature in the free atmosphere is of significance for weather prediction and climate monitoring. Radiosondes are used to measure essential climate variables in upper air. Herein, an upper-air simulator is developed, and its performance is evaluated to improve the measurement accuracy of radiosondes by reproducing the environments that may be encountered by radiosondes. The paper presents a methodology to correct the main source of error for the radiosonde measurements.

Heating by solar radiation is the dominant error source for daytime temperature measurements by radiosondes. This paper describes a new laboratory setup (SISTER) to characterise this radiation error for pressures and ventilation speeds that are typical for the conditions between the surface and 35 km altitude. This characterisation is the basis for the radiation correction that is applied in the GRUAN data processing for the RS41 radiosonde. The GRUAN data product is compared to that of Vaisala.

A model was developed to quantitatively describe the dynamics, in terms of vapor-phase water concentration and isotope ratios, of nanoliter-droplet evaporation at the end of a syringe needle. Such a low humidity generator can be used to calibrate laser-based water isotope analyzers, e.g., in Antarctica. We show that modeling of experimental data constrains isotope fractionation factors and the evaporation rate to physically realistic values in good agreement with available literature values.

We describe the Roland von Glasow Air-Sea-Ice Chamber, a laboratory facility for studying ocean–sea-ice–atmosphere interactions. We characterise the technical capabilities of our facility to help future users plan and perform experiments. We also characterise the sea ice grown in the facility, showing that the extinction of photosynthetically active radiation, the bulk salinity, and the growth rate of our artificial sea ice are within the range of natural values.

Icing is a severe problem in many technical applications like aviation or high-voltage components for power transmission and distribution. The presented experimental setup enables the accurate investigation of the freezing of water droplets under the impact of electric fields. All boundary conditions are well controlled and investigated in detail. Results obtained with the setup might improve the understanding of the freezing process of water droplets under the impact of high electric fields.

In this work we present experimental results of a novel actively heated fiber-optic (AHFO) observational wind-probing technique. We utilized a controlled wind-tunnel setup to assess both the accuracy and precision of AHFO under a range of operational conditions (wind speed, angles of attack and temperature differences). AHFO has the potential to provide high-resolution distributed observations of wind speeds, allowing for better spatial characterization of fine-scale processes.

We present a cheap, adaptable, and easily assembled thermal sensor for detecting microlitre droplets of water freezing. The sensor was developed to increase the level of automation in droplet array ice nucleation experiments, reducing the total amount of time required for each experiment. As a proof of concept, we compare the ice-nucleating efficiency of a crystalline and glassy sample of K-feldpsar. The glassy sample was found to be a less efficient ice nucleator at higher temperatures.

Most observations of the atmosphere are point observations, which only measure a small area around the sensor. This limitation creates problems for a number of disciplines, especially those that focus on how the surface and atmosphere exchange heat, mass, and momentum. We used distributed temperature sensing with fiber optics to demonstrate a key breakthrough in observing wind direction in a distributed way, i.e., not at a point, using small structures attached to the fiber-optic cables.

The procedure for preparing electrochemical concentration cell (ECC) ozonesondes are considered to be standardized, but there remains the question of actual measurement accuracy, believed to be 5–10 %. It would be ideal to include a reference instrument on the balloon flight to aid in checking ECC accuracy and reliability. Balloon-borne reference instruments are not usually available, mostly because they are too expensive for other than occasional use.

Snow, frost formation and ice cubes in our drinks are part of our daily life. But what about our technical innovations like aviation, electrical power transmission and wind-energy production, can they cope with icing? Icing Wind Tunnels are an ideal laboratory environment to answer that question. In this paper, we show how the icing wind tunnel in Braunschweig (Germany) was built and how we can use it for engineering and climate research.

The CERN CLOUD chamber is used to understand different processes of particle formation in the atmosphere. This information can be used by global climate models to update the influence of cloud formation. To provide the most accurate information on these processes, a thorough understanding of the chamber is necessary. Temperature measurements were performed inside the entire volume of the CLOUD chamber to ensure temperature stability and more accurate estimations of particle formation parameters.