A vertical scaling pattern is the better-known scenario. This pattern spreads different components of one application across different clouds. An example of this would be where one part of an application, typically the data, is kept private, while another part is run in the cloud, such as the web front end or calculations being made on the data.
A horizontal hybrid cloud scaling pattern, on the other hand, spreads different instances of applications across different clouds. In this scenario, enterprises develop their own applications and run them in multiple environments, some on-prem, some in the cloud. Developers run it in a test environment, testers test it in a QA environment, and users access the version that has been deployed to the production environment. Each of these environments can be in the cloud or on-prem depending on the security, performance, flexibility and scalability requirements of that environment.