Ask HN: Where do I learn about the working of Web applications on the cloud?

When I starting using Heroku, I was desperately trying to understand what the dyno(s) are and how the processes work. While I can write web applications in python .etc., I only understand the obvious from the functioning of these "cloud application platforms" and I feel it is not enough at all. Similarly for Node.js.

Could you direct me towards some good books and/or resources which talks about these things?