Earth science - weather, atmosphere, and astronomy
What the exam tests
Atmosphere, weather, seasons, Moon phases and the solar system. Expect explanations of pressure, fronts, day length and why phases occur.
Core rules
- The atmosphere is layered; most weather occurs in the troposphere. Air pressure falls with altitude.
- Warm air rises and expands, cooling to form clouds; high pressure brings sinking, clear weather.
- A front is a boundary between air masses; warm fronts bring steady rain, cold fronts bring heavy showers.
- Seasons are caused by Earth's axial tilt, not distance from the Sun. Summer has a higher Sun and longer days.
- Moon phases depend on the angle between the Moon, Earth and Sun as the Moon orbits. A lunar eclipse occurs when Earth's shadow falls on the Moon.
- The solar system has eight planets; inner planets are rocky, outer planets are gas or ice giants.
Worked example
Why is summer hotter in Fukui than winter? Earth's axis is tilted about 23.5°. In summer the Northern Hemisphere tilts toward the Sun, so sunlight strikes at a higher angle, spreads over less area, passes through less atmosphere, and days are longer. In winter the same region tilts away, so the Sun is lower and days are shorter.
Traps
- Seasons are not caused by Earth being closer to the Sun; that would affect both hemispheres equally.
- Moon phases are not Earth's shadow; that is an eclipse.
- High pressure is not always “bad weather”; it usually means clear, settled conditions.