Sometimes cats will vomit when they eat too fast. Is it a wet or dry food? If she vomits and the hard food is still whole then she is probably just swallowing it too fast. She probably isn't eating that fast at night because she wasn't as hungry. My cats sometimes do this when I give them wet food, which is rare. They get so excited that they just eat it as fast as they can and then vomit it back up after a minute. You can try a few things to help prevent this if she is eating too quickly. One thing you can do is get a raised bowl, which will make her eat slower. You can also spread out the food more on a bigger plate. Even trying to give her a smaller portion at first could also help. Let me know if it seems like she's eating too fast. I'll be glad to help with other questions.
