Niebla vs. neblina
The Spanish words 'niebla' and 'neblina' both refer to the meteorological phenomena commonly known as fog, mist, or haze. However, there is a slight difference in their usage depending on the intensity and density of the phenomenon they describe.
Niebla
'Niebla' refers to a more dense, thick, or heavy type of fog or mist that notably reduces visibility. This term is typically used when the meteorological conditions are quite severe.
La niebla era tan densa que apenas podíamos ver el camino.
(The fog was so dense that we could barely see the road.)
Es peligroso conducir en condiciones de niebla.
(It is dangerous to drive in foggy conditions.)
Neblina
'Neblina', on the other hand, refers to a lighter, less dense type of fog or mist. It reduces visibility but not as severely as 'niebla'.
Desperté temprano y vi la neblina saliendo del lago.
(I woke up early and saw the mist rising from the lake.)
En la mañana había una suave neblina.
(There was a gentle mist in the morning.)
Summary
While 'niebla' and 'neblina' both refer to types of fog or mist, 'niebla' refers to a more severe, heavy, denser form that significantly reduces visibility. On contrary, 'neblina' denotes a lighter, less dense form of fog or mist.