Cloud Academy II

Les Houches School of Physics

( 8 – 13 March 2020 –>  
6 – 11 March 2022 –>
26 – 31 March 2023)

Update, September 2022: Cloud Academy II will be again postponed to March 2023 
Update, June 2020: Cloud Academy II will be held 26 – 31 March 2023 in Les Houches l’Ecole de Physique

Important update, 2 March 2020: We are very sorry for having to postpone Cloud Academy II, hence, for cancelling the winter school at Les Houches that was planned for 8-13 March 2020. The probability that travel and logistical disruptions as result of the corona virus spreading will affect Cloud Academy II participants is too high. Various institutes and universities have already imposed travel restrictions such that lecturers and speakers had to drop out.

The SOC was very impressed by the interest and enthusiasm of the Cloud Academy community and by the quality of the submitted abstracts. Building on the strong response and interest we hope to be able to re-schedule the school in the near future.



Clouds and hazes form in nearly every type of planetary atmospheres. They fundamentally impact the atmospheric structure and spectra of exoplanets and even influence their habitability. Intensive observing efforts have generated an abundance of data on clouds and hazes in exoplanets but modeling expertise in the community has lagged. This school will focus on physical models for cloud and haze formation in planetary atmospheres in different radiation environments, and include reviews on exoplanet observations and laboratory studies.
The previous sessions (e.g. Cloud Academy I) focused on atmosphere circulation and the general concept of cloud formation in exoplanet and solar system planets. The present session forges a closer link to observations through detailed atmosphere models as exoplanet research is now developing into the characterization of exoplanets. We therefore aim to establish an ongoing effort to help the community keep up to date and exchange ideas on this rapidly developing field.

Organisational Committee:

Christiane Helling (Centre for Exoplanet Science, University of St Andrews)
Daniel Apai (University of Arizona)
Mickaël Bonnefoy (Université Grenoble Alpes)
Nicolas Iro (University of Vienna Observatory, University of Vienna)
Mark Marley (NASA Ames Research Center)
Véronique Vuitton (Institut de Planétologie et d’Astrophysique, Université Grenoble Alpes)

Preceding sessions:
2017: Diversity of planetary circulation regimes, in our solar system and beyond (Nicolas Iro, Chair)
2018: Cloud Academy I (Daniel Apai, Chair)

Contact us:

Any questions, please email: da16 at

Application & Registration:

We anticipate a significant oversubscription to the school, the attendance of which is limited to sixty participants.

Application is now closed (application form).
Application deadline: 15 September 2019.

Please complete the application form if you wish to apply for the school. No payment or commitment is required for the application. We anticipate notifying the selected the participants latest by December 1st. Selected participants will then be asked to confirm their participation latest by December 15th. The school registration fee is 550 Euro, which includes the accommodation, food, school expenses, and coffee breaks. The registration fee will be paid directly to the school on-site.

Venue & Lodging:

The official program of the school starts on 9 March 2020, 9:00h. Participants needs to leave the School by 16:00h on 13 March 2020.

The school will be held a the Les Houches Advanced School for Physics in the French Alps. The school is known for its long tradition of highly interactive, focused, and high-level schools on the frontiers of physics. The Les Houches School will offer accommodation on site, in charming chalets scattered on the hillside with a majestic view of the Mt Blanc. The school’s modern lecture hall provides an ideal setting for presentations and discussion sessions. The on-site restaurant provides breakfast, lunch, and dinner for the participants. The costs of the accommodation and food are included in the school registration fee.


see Les Houches School of Physics

The best way for participants to reach the school is from the Geneva airport via Mountain Dropoffs shuttle service. Reservations can be made and paid for on line. Taking the train from Grenoble will require a taxi to the school. That needs to be pre-arranged as there are no services at the train station.

Science Programme:

The school will consist of invited lectures, invited review talks, contributed talks, posters, and extended discussion sessions. The invited lectures will provide a thorough introduction to the key topics covered in the school and will be accompanied by practice / hands-on sessions, where participants put in practice what they have learned in the lectures. Invited review talks will provide overviews of the frontiers of the relevant fields. Contributed talks and posters will bring exciting new results to the school and will help engage the participants in the scientific discourse.

Les Houches Cloud Academy II Program

Size: 114 x 114 cm
Cloud Academy II will have 36 poster presentations and all posters will be given a lightning talk slot. In order to allow everybody to show their posters, poster place change-over will be on Wednesday morning. The first set of posters will be on display from Monday – Tuesday evening, the second set of posters from Wednesday morning to Friday coffee-break. We will have three dedicated poster events: the lightning talks on Monday, and two poster sessions (Monday from 10.45-12:00h and on Wednesday from 14:30h to 16:00h). Please see the program pdf-file for more details.

Lecturer and Invited speakers (confirmed):

Daniel Apai: time-domain observations to probe atmospheric properties + activity
Mark Marley: radiative transfer modelling for planetary atmospheres, radiative heating/cooling, Mie scattering, optical properties
Christiane Helling: Detailed cloud modeling
Mickaël Bonnefoy: clouds in directly imaged planets and free-floating analogues
Véronique Vuitton: spectrometry for characterization of the molecular composition of complex organic material
Henrik Svensmark:  cosmic ray ionization, clouds and climate
Theodora Karalidi: phase curve modelling
Ruth Signorell: characterisation of single aerosol particles by optical trapping
Michiel Min: Artful Retrieval
Daphne Stam: polarimetry
tbd: dynamic atmospheres

School Programme and Online material:

Les Houches Cloud Academy II Program


We grateful to  the CNRS

for financial support of the whole school.

The RAS plans to provide specific support to UK students and postdocs.