Fig. 4.

Variation of the monthly median values of Hm in km, at El Arenosillo, for the four seasons (a) winter, (b) spring, (c) summer, (d) fall and for the high solar-activity year 2000 and for the low solar-activity year 2007.
Variation of the monthly median values of Hm in km, at El Arenosillo, for the four seasons (a) winter, (b) spring, (c) summer, (d) fall and for the high solar-activity year 2000 and for the low solar-activity year 2007.