Drawing the line of the sun
The drawing was included in the exhibit Alvar Aalto 1898-1976. Organic Architecture, Art and Design, Caixa Forum in Barcelona, published in the exhibition catalog Alvar Aalto: Second Nature. From: http://solarhousehistory.com/blog/2013/7/19/tb2 Anthony Denzer, Ph.D., M.Arch. University of Wyoming.
Alvar Aalto used solar geometry diagrams in the design of the Paimio Sanatorium, drawing different angles of sunlight to ascertain how light would enter patient rooms, enhancing their therapeutic treatment. The above image shows winter sunlight at an angle of 34˚.