The phrase "solar shortwave" refers to a type of energy or radiation that comes from the Sun. It is a form of electromagnetic energy that has a short wavelength. Full definition
Now if the entire process were instant there would be no problem but it all takes time for air to rise and then fall so the process is out of phase with the normal radiative flow of solar shortwave in and longwave out and has been since the very first atmospheric molecules floated above the surface. (newclimatemodel.com)
Figure 2: Break - up timing and solar shortwave energy incident at the surface (mean and cumulative shown on bottom and left axis, respectively) for 2009 (thick red line) and other recent years. (searcharcticscience.org)
In 2) i wanted to discuss the different forcing efficacies of solar shortwave compared to anthro fossil carbon combustion upon global average surface temperature, rather than the emission temperature at top of atmosphere (realclimate.org)