Weather balloon
A balloon used to measure conditions in the atmosphere. Scientists attach a measuring device called a radiosonde to the balloon before sending it floating upwards to take measurements and transmit them back to scientists on the ground.
Scientists around the world release about 1600 weather balloons each day.
Satellite
Any object in orbit around a larger body. Satellites can be natural – such as the Moon – but more often the term is used to refer to an object made by humans which is orbiting the Earth. Scientists use these satellites to collect data about the Earth, its weather and its climate.
Stevenson screen
A box containing measuring devices at a weather station which protects the instruments inside against damage, whilst still allowing air to circulate freely around them.
Argo float
A floating instrument which continually monitors the temperature and other properties of the oceans, to a depth of about 2 km. The floats rise and sink every few days, taking measurements as they do so. Scientists use over 3000 of them worldwide to measure changes in ocean conditions.
Radiosondes
Sensors attached to a weather balloon that measure atmospheric conditions. As the balloon rises upwards, the radiosonde takes various measurements including temperature, pressure and humidity and sends the results back to scientists on the ground.
Proxy
An indirect measurement of the climate obtained from natural records. For example, each year a tree forms a new ring in the cross section of its trunk. The thickness of the rings corresponds to how much the tree grew in a particular year, which in turn depends on the climatic conditions of that year.
So scientists measure the thickness of the rings to build up a picture of the climate in the past. Other examples of proxy data include ice cores, stalactites and sediment cores.
Ice core
A column of ice extracted from the Greenland or Antarctic ice sheets. Scientists can use ice cores to investigate the amount of greenhouse gases in the atmosphere up to 800,000 years ago. The bottom of the longest ice core came from nearly 3.5 kilometres deep. The deeper scientists drill, the further back in time they can examine.
Corals
A marine animal closely related to sea anemones that encases itself in a self-constructed hard calcium shell.
Corals exist in water of a very specific temperature at shallow depths where there is plenty of light.
Often corals group together to form coral reefs – some of the most ecologically diverse regions on Earth.
Climate
A summary of the weather in a particular region over a period of at least ten years, but more commonly defined over 20 - 30 years. The climate describes both the average weather conditions (for example temperature, rain, snow and wind) in a particular region as well as the extremes.
