Unit 18 Vocab — Science

Atmosphere

The envelope of gases that surround our planet

Homosphere

A layer of earth’s atmosphere in which there is a uniform mixture of gases

Heterosphere

A region of the earth’s atmosphere in which there are distinct layers of different gases

Troposphere

The lowest temperature layer of the earths atmosphere, extending from ground level to about 11 km. This is the location of most of earth’s weather.

Lapse Rate

A steady drop of temperature altitude in the troposphere

Stratosphere

The second layer in the earths atmosphere starting above the troposphere (11 km and continuing to 50 km). Temperature increases with altitude

Jet Stream

A belt of high speed winds in the stratosphere that flows across the upper and middle latitudes

Mesosphere

The third layer starting above the stratosphere (50km and continuing to 80km) it contains the coldest temperatures in the atmosphere – -90°C

Thermosphere

The fourth layer in the earths atmosphere; starts above the mesosphere (80km - 500km) it contains the hottest temperatures in the atmosphere

Exosphere

The fifth layer in the earths atmosphere starting above the thermosphere – above 500 km – where atmosphere thins into interplanetary space

Ozone Layer

A layer of concentrated ozone in the stratosphere that shields the earth from harmful ultraviolet light (20km-50km)

Ionosphere

A region of variable height in the earths atmosphere where solar radiation breaks gas molecules into ions – 75 to 500°C

Magnetosphere

The geomagnetic field that surrounds the Earth originating in the earths interior – extending to 160,000 km

Solar constant

The flow rate of radiant energy from the sun through space to reach earth. At the top of the atmosphere it is = 1.367kW/m²

Radiation

The admission of electromagnetic waves, such as sunlight or heat lamps. A method of transferring thermal energy even in a vacuum.

Conduction

The movement of thermal energy through medium. The transfer of thermal energy by direct contact between two substances.

Convection

The transfer of thermal energy by the flow of a fluid caused by differences in density. Warmer, less dense material moves upward, as it’s displaced by a cooler, more dense fluid.

Greenhouse Effect

A process by which a planets atmosphere keeps energy from being lost to space. The effect protects life on earth by retaining sufficient energy to maintain liquid water.

Greenhouse Gas

Natural atmospheric gases, such as water vapor, carbon dioxide, and methane that warmed the atmosphere by the greenhouse effect