altitude /ˈæltɪtjuːd/ noun

1. The altitude of a place is its height above sea level.
2. The altitude of an object, especially an aircraft or a satellite, is its height above the ground or above a particular point on the ground.

atmosphere /ˈætməsfɪə(r)/ noun

1. The atmosphere of a place is the mixture of gases around it.
2. The atmosphere of a place is the mood or feeling that you have in it.

carbon dioxide /ˌkɑːbən daɪˈɒksaɪd/ noun

Carbon dioxide is a gas that is produced when people and animals breathe out or when certain fuels are burned. It is also produced by plants.

core /kɔː(r)/ noun

1. The core of something is the central and most important part of it.
2. The core of the earth or another planet is the central part of it.

crust /krʌst/ noun

1. The crust on bread or pastry is the firm outer layer of it.
2. The crust of the earth or another planet is the hard outer layer of it.

disaster /dɪˈzɑːstə(r)/ noun

A disaster is a very bad accident or event that causes a lot of damage or harm. If you describe something as a disaster, you mean that it is very bad and is likely to end in failure or defeat.

horizon /həˈraɪzn/ noun

1. The horizon is the line in the distance where the sky and the land or the sea seem to meet.
2. If something is on the horizon, it is going to happen or appear soon.

hydrogen /ˈhaɪdrədʒən/ noun

Hydrogen is a gas that has no colour or smell, and is the lightest and simplest chemical element.

hydrosphere /ˈhaɪdrəsfɪə(r)/ noun

The hydrosphere is the part of the Earth’s surface that is covered by water.

latitude /ˈlætɪtjuːd/ noun

1. Latitude is the distance of a place north or south of the equator, measured in degrees.
2. If you say that someone has latitude to do something, you mean that they have freedom to decide how to do it.

lithosphere /ˈlɪθəsfɪə(r)/ noun

The lithosphere is the solid outer layer of the earth that consists of the crust and the upper part of the mantle.

longitude /ˈlɒŋɡɪtjuːd/ noun

1. Longitude is the distance of a place east or west of a particular line, usually an imaginary one, called the prime meridian, measured in degrees.
2. If you say that someone has longitude to do something, you mean that they have a long period of time in which to do it.

mantle /ˈmæntl/ noun

1. The mantle of something is the layer of it that surrounds or covers the central part.
2. The mantle is the layer of the earth below the crust and above the core.

oxide /ˈɒksaɪd/ noun

An oxide is a compound of oxygen and one or more other elements.

oxygen /ˈɒksɪdʒən/ noun

Oxygen is a gas that is in the air and that animals and humans need to breathe in order to live. It is also used in various industrial processes.