Absolute zero is the coldest possible temperature in the universe. In the Kelvin scale, absolute zero is 0K and in the Celsius scale it is -273°C.

A compound is a substance containing two or more different chemical elements bound together by a chemical bond. In covalent compounds, electrons are shared between atoms. In ionic compounds, one atom borrows an electron from another atom resulting in two ions (electrically charged atoms) of opposite polarities that then become bonded electrostatically.

The carbon cycle represents the ciruit of carbon through Earth's ecosystem. Carbon dioxide (CO₂) in the atmosphere is absorbed by plants through photosynthesis. Plants then die and release carbon back into the atmosphere during decomposition or are eaten by animals who breathe (respiration) the carbon into the atmosphere they exhale and produce waste which also releases carbon as it decays.

Mega (M) is 10⁶, kilo (k) is 10³, centi (c) is 10^-2, milli (m) is 10^-3 so 1 ML represents the largest value.

Cirrus clouds are thin, wispy high-altitude clouds composed of ice crystals that originate from the freezing of supercooled water droplets. Cirrus clouds generally occur in fair weather and point in the direction of air movement at their elevation.