Long-term series of historical observations in Latvia of mesospheric clouds are digitized. Observational data are freely available to researchers. Observation sites, methodologies, and technical support are described. This article provides a brief overview of mesospheric cloud observation statistics for 1957–1983.

The manuscript pesents the first-ever empirical study supported by historcal records which strongly indicates that portolan charts are copies of maps from classical antiquity. Their sub-parts were likely derived from maps in the equidistant cylindrical projection that were graphically adjusted to partially resemble a map in conic projection. It also provides a detailed historical overview of the most significant cartometric studies on portolan charts conducted over the past century and a half.

A detailed history of the Max-Planck-Institut für Aeronomie (MPAe), including its research and deleopment.