blindingly

https://tts.langeek.co/read?text=YmxpbmRpbmdseQ&hash=83a347aeef22b09c4ef2b06d1d5e78937948def7&lang=en&cache-only=0&driver=googletts&accent=US

These adverbs describe the amount of light that is available in a specific context, such as "dazzlingly", "brightly", "dimly", etc.