Learn Italian: Non ci vedo chiaramente nella penombra. - I don't see clearly in the dim light.

The verb here is the pronominal verb vederci. Adding ci to vedere shifts the meaning from seeing a specific object to the physical ability to see. Non ci vedo means "I can't see" in a general physical sense, whereas non vedo usually requires a direct object, like "I don't see the car".

Does the ci here mean "there" or "us"?

Neither! This is the ci attualizzante. It is a fixed part of the verb vederci used to express sensory capacity. While ci often means "there" or "to us" in other contexts, here it simply changes the meaning of vedere to focus on the biological function of your eyes.

Could I say non riesco a vedere or non posso vedere instead?

You could say non riesco a vedere, but non ci vedo is much more common and idiomatic. While English relies heavily on "can" or "can't" for sensory abilities ("I can't see"), Italian prefers using verbs like vederci and sentirci directly to express that environmental factors or physical limits are hindering your senses.

What is the origin of the word penombra?