Parts per million

 A unit of measurement that can be used to describe the concentration of a particular substance within air, water, soil, or some other medium. For example, the concentration of carbon dioxide in the Earth’s atmosphere is almost 400 parts per million, which means 1 million liters of air would contain about 400 liters of carbon dioxide.

Adaptation

Taking actions to avoid, benefit from, or deal with current and future climate change. Adaptation can take place in advance (by planning before an impact occurs) or in response to changes that are already occurring. Taking actions to avoid, benefit from, or deal with current and future climate change. Adaptation can take place in advance (by planning before an impact occurs) or in response to changes that are already occurring.

Ultraviolet (UV) radiation

Ultraviolet (UV) radiation: A type of electromagnetic radiation that is produced by the sun. UV radiation is not visible to the naked eye. Most UV radiation is blocked by ozone high in the Earth's atmosphere, but some of it reaches the Earth’s surface. Being exposed to too much UV radiation can cause a sunburn, and over time it can lead to skin cancer and eye damage. Too much UV radiation can also harm plants.

Sunspot

Sunspot: A dark area that forms and disappears on the surface of the sun over periods of days or weeks. The amount of sunspot activity varies over time, but it tends to follow a roughly 11-year cycle. This sunspot cycle causes slight differences in the amount of energy that the sun gives off.