晴天

1. Origins, structure, and basic meaning

• Structure: 晴天（せいてん） is a noun meaning clear weather. 晴 indicates a clear state and 天 refers to the sky or weather.
• Basic usage: It can describe the weather, as in 晴天だった, or its continuation, as in 晴天が続き.

2. Common pitfalls and similar expressions

• A noun for the weather
  • 晴天 names a weather condition, while 晴れる is a verb describing the weather clearing.
• A more specific condition in the example
  • 晴天 means clear weather; 雲一つない晴天 in the first example adds the description that there was not a single cloud.