Breakdown of Com esta ventania, as ondas devem de estar enormes.
estar
to be (temporary / location)
com
with
este
this (+ noun)
as
them (f)
Questions & Answers about Com esta ventania, as ondas devem de estar enormes.
Why does the sentence use devem de estar instead of just devem estar?
Adding de after dever specifically marks probability or a logical assumption ("they must be huge"). This is the focus of your current lesson! Without the de, dever strictly implies obligation ("they ought to be huge"), although in casual spoken Portuguese, people often drop the de even when making assumptions. Including it makes your meaning completely unambiguous.
Is ventania related to the word vento?
Yes, it is an augmentative form. The suffix -ania is used to create nouns that indicate a large amount or intense degree. Here, it turns vento (wind) into ventania (a gale, windstorm, or very strong wind).
Why use estar instead of ser for the waves being huge?
We use estar because the huge waves are a temporary state directly caused by the current weather (esta ventania). If you used ser, you would imply that the waves at this specific location are permanently huge, completely regardless of the wind.
Could I say por causa desta ventania instead of com esta ventania?