Where?
Hemisphere, latitude, elevation, coastlines and local surfaces can change the seasonal signal.
Orientation / begin with the word
What is summer?
There is no single globally sufficient answer. “Summer” may name an astronomical interval, a meteorological statistics window, a biological phase, a local climate pattern or a cultural season.
Four questions
Before you use the label, choose the lens.
When?
A solstice, a three-month statistics window, a biological phase and a school holiday can all draw different boundaries.
What evidence?
Separate direct observation from historical typical patterns, physical explanation, editorial interpretation and cultural convention.
What is the task?
Climate comparison, field observation, visual design and travel planning need different kinds of seasonal evidence.
Misconception check
Summer is not caused by Earth simply being closer to the Sun.
Fact · physical mechanism
NASA explains Earth’s seasons primarily through axial tilt and changing sunlight geometry as Earth orbits the Sun. The two hemispheres experience opposite seasonal phases.
Sources: NASA Space Place · What Causes the Seasons? · NASA Science · Helio and You: Seasons on Earth, Mars, and Beyond