What's the difference between the humid subtropical climate and oceanic climate?

My friend, I have read about meteorology in French (my mother tongue) in Norwegian (the language spoken where I live) and in English (the language of aviators, since I am a pilot). Our weather is about the differences of temperature, pressure and moisture of our atmosphere in different regions. Anything else is trying to put in words simple laws of physic. What is a "humid" climate? It is probably the definition that the book you read uses.

Let's have a try. An oceanic climate would mean the vicinity of a large body of water. Its influence would be that of a heat regulator: milder winters and cooler summers. If the prevailing weather pattern is to bring that maritime moist air over land, then it would be a humid climate, but not necessarily.

A humid subtropical climate doesn't have to be close to an ocean - although it helps - but must have prevailing winds that bring moist maritime air over the land. And that would be, in my humble opinion, the difference between the two: the direction of the prevailing winds.

The notion of "humid" can be a tricky one. At a certain temperature, a certain volume of air can only contain a certain volume of water. When it happens, that air parcel is said to be saturated and the relative humidity is 100 percent. But the absolute humidity; the actual amount of water, varies a lot with the temperature. For example, a freezing point, a cubic meter of air can't hold much more that 5 grams of water. But at say, 15 C, it is up to 13 grams!

Air that rises cools down by the so-called adiabatic effect of a lesser pressure aloft. If a relatively dry air rises over a mountain, it will cool down and end by reaching saturation temperature (called the dew point temperature) and condense as clouds. So, a relativel dry air can generate a humid climate if observed up in a mountain. You'll find that e.g. along the coast of Chile. The coastline is dry but up in the mountains, it is possible to grow vegetables simply from the dew forming on all objects. I have observed the same on e.g. the Cape Verde islands in the Atlantic. It hardly rains at all at that latitude but growing is possible on the top of the vulcanic islands because of the ever lasting clouds forming from the oceanic air rising over the mountains.