The word "夏天" is formed by combining the character 夏, which historically represents the concept of summer, often depicted in ancient scripts as a person with seasonal attributes, and the character 天, which originally meant "sky" or "heaven" but here extends to denote "day" or "season". Together, they create a compound where 夏 specifies the warm season and 天 broadens it to encompass the entire period or the natural realm of that time, thus directly constructing the term for summer through this meaningful juxtaposition of ideographic elements.