Earth science: time, weather and models
Build a geological sequence from stated relationships rather than a page position. In an undisturbed sedimentary sequence, lower layers were deposited before higher layers. An intrusion or fault is younger than the rocks it cuts. Folding occurred after the affected layers formed. These are relative-age statements and do not supply a numerical date without additional evidence. A fossil can support an environmental interpretation, but transport, the organism involved and other observations matter. Neither a single shell nor a single plant fragment uniquely establishes an entire ancient climate.
Distinguish the earthquake focus inside Earth from the epicenter directly above it. A difference between P-wave and S-wave arrival times can estimate distance from the seismic source using a stated wave-speed model. It does not automatically equal epicentral surface distance; source depth and geometry matter. Compare measurements at multiple locations when locating a source. For celestial observations, Earth's rotation explains the principal daily apparent motion, while revolution together with axial tilt explains seasonal changes. The seasons are not primarily a consequence of Earth being closer to the Sun.
Weather data require definitions and context. Wind direction conventionally names the direction from which the air comes. A cold-front passage may be associated with wind, temperature and pressure changes, but any one sign alone is insufficient to establish a front or a forecast. Relative humidity compares actual water-vapor pressure with saturation vapor pressure at the same temperature. In a specified constant-volume school calculation, vapor density and a supplied saturation density can be used as a corresponding ratio. Cooling can produce condensation when the saturation capacity falls below the supplied vapor amount. Identify whether vapor can enter or leave the modeled parcel before calculating a condensed mass.