雨順風調The rain (雨) is gentle (順), the wind (風) appropriate (調).
順調 (순조) can mean "favorable," "smooth," "satisfactory," "seasonable," "normal," or "appropriate." So, what did the Chinese consider "favorable" or "appropriate" in regard to wind and rain? Well, the following expression supposedly has a similar meaning to the one above:
[Every] fifth [day] (五) wind (風); [every] tenth (十) rain (雨).
Therefore, the above expressions seem to suggest that receiving rain once every ten days was considered an appropriate amount of rain, probably for raising crops. Wind also seems to have been recognized as playing a role in the growth of crops and plants.