The sky is overcast so there is no sunshine, and you want to ask someone if they could feel sunshine which isn't present. Do I still need to add "the" with sunshine?
- Can you feel sunshine?
- Can you feel the sunshine?
In the context of your question, the first choice is probably better. Your first sentence, without "the", implies that the speaker may or may not feel sunshine, and is in a sense asking for confirmation. The second sentence, with "the" implies that the speak does feel the sunshine, and is asking if the other person can feel it as well.
"Can you hear bells?" - I think I might hear bells, but it could be a ringing in my ears.
"Can you hear the bells?" - I can hear the bells and want to know if you do too.
Once when I was a child, there were tornadoes in our area, and we were in our basement. At some point, the sun came out, and I said that I saw sunshine. Not the sunshine, but sunshine; the sunshine that was shining through our basement window.
Leaving out the implies a quantity of sunshine, sunshine as applied in some context. Some sunshine, in other words. Consider these three sentences:
Sunshine is the best source of Vitamin D.
To get Vitamin D, go out and get some sunshine.
To get Vitamin D, go out in the sunshine.
The first two imply that sunshine is a quantifiable resource, whereas the last one references all sunshine.
An analogous concept is the sky. As a child, I was afraid of thunderstorms. If the clouds got dark, I would look for a patch of blue sky. If I found one, I would say that there wasn't going to be a thunderstorm, because I could "see blue sky."
It's difficult to imagine someone asking your questions naturally without the help of clarifying body language or tone. To avoid confusion, you could ask: