As I get it, shortwave solar radiation penetrates the atmosphere to the earth's surface, where it is transformed into longwaves readily absorbed by carbon dioxide and other gases; that supposedly traps the heat and causes the earth's climate to warm.

Jacobsen, Trond, "ZEVS, the Russian 82 Hz ELF transmitter: An Extrem Low Frequency transmission-system, using the real longwaves" ALFLAB, Halden, Norway.

Its length scale is much smaller than that of longwaves, which are responsible for synoptic scale systems, although shortwaves may be contained within or found ahead of longwaves and range from the mesocale to the synoptic scale.