Figure 1

Diurnal heating by the Sun generates large scale convective flows adjacent to the Earth’s surface, modulated with daily, \(f_{{\text{d}}}\), and yearly, \(f_{{\text{y}}}\), frequencies (a). These flows can be modeled by periodically modulated Rayleigh–Bénard experiments performed in the cryogenic environment using the “thermally fast” experimental cell (b) equipped with various temperature sensors (the sensor Ge05 highlighted), as described in more detail in "Methods".