The query "why is" is incomplete and ambiguous on its own and does not specify what exactly is being asked. Since it lacks further context or a complete question, it cannot be directly answered as-is. To offer useful information, clarifying or completing the question would be necessary, such as "why is the sky blue?" or "why is water wet?". If the intended question involves a common "why is" question like "why is the sky blue," I have found explanations regarding the reason the sky appears blue. The sky appears blue because of a process called Rayleigh scattering, where shorter wavelengths of light such as blue are scattered more by the tiny molecules in Earth's atmosphere than other colors. This scattering causes more blue light to be visible from all directions in the sky during the day. Please specify the complete question or the topic of the "why is" question for a precise and full answer.