Convention current is the entire chunk of liquids or gas that move from one place to the other. It is not just the transfer of heat and energy but the mass movement of fluids as well. This transfer drives the oceans’ current and the atmospheric weather. Since heated fluids like the ocean’s water bodies are less dense, according to science, they will rise up above and pull the cooler air into its place. There are various conventions, which include oceans, air, and water conventions. They all follow the same principles and as a result affect weather and climate.
Making a haiku longer would water it down as a poem. Haiku are especially effective because words are used sparingly. Also, you read a haiku over a couple of times because you realize there’s more to the poem than you noticed at first.