Sunny day walk and looking at the sky

I took some pictures while I was outside during my lunch break. Went to the same waterfront walkways as last week. It seems to be a popular spot during sunny days, both for humans and the cormorants.

And as I was heading home in the afternoon, I saw the sky covered by two types of clouds and they were divided evenly too. Such a strange phenomenon (for me, at least). I wish I know more about meteorology to be able to read the clouds.