Nuvoloso vs. coperto
The Italian words 'nuvoloso' and 'coperto' both describe cloudy weather conditions, but they have distinct nuances in their meanings and usage.
Nuvoloso
'Nuvoloso' refers to a sky that is partially cloudy or has scattered clouds. It indicates that there are noticeable clouds in the sky, but clear patches are still visible.
Oggi il cielo è nuvoloso, ma si vede ancora un po' di azzurro.
(Today the sky is cloudy, but you can still see some blue.)
Il meteo prevede una giornata nuvolosa con schiarite nel pomeriggio.
(The weather forecast predicts a cloudy day with clearings in the afternoon.)
Coperto
'Coperto' describes a sky that is completely overcast, with clouds covering the entire visible sky. It suggests a more uniform and dense cloud cover than 'nuvoloso'.
Il cielo è completamente coperto, sembra che possa piovere da un momento all'altro.
(The sky is completely overcast, it looks like it might rain at any moment.)
Durante l'inverno, in questa regione il cielo è spesso coperto per settimane.
(During winter, in this region the sky is often overcast for weeks.)
Summary
While both 'nuvoloso' and 'coperto' describe cloudy conditions, 'nuvoloso' indicates a partially cloudy sky with some visible clear areas, whereas 'coperto' refers to a fully overcast sky with no visible clear patches. 'Nuvoloso' suggests a less severe cloud cover compared to the more complete and potentially gloomy connotation of 'coperto'.