The layer of air immediately adjacent to the Earth's surface where air circulates in great vertical and horizontal convection currents, constantly redistributing heat and moisture around the globe
Its depth ranges from about 18 km over the equator to about 8 km over the poles
Contains about 75 percent of the total mass of the atmosphere
Air temperature drops rapidly with increasing altitude, reaching about -60°C at the top
The third layer of the atmosphere directly above the stratosphere and directly below the thermosphere
Temperature decreases as altitude increases
Begins at the top of the stratosphere and ends at the mesopause, the coldest part of the Earth's atmosphere with temperatures below -143 degrees Celsius
Proxy data refers to scientific data that are not strictly climatic but can be correlated with climate data, such as the temperature of the land or sea
Polar ice caps and mountain glaciers have an accumulation record of snow that has been transformed into glacial ice over hundreds to thousands of years, containing small bubbles of air deposited at the time of the storm, allowing measurement of atmospheric gases like CO2 and CH4
The growth of trees is influenced by climate, both temperature and precipitation, with wider rings indicating good growth conditions and narrower rings indicating poor conditions, providing a proxy record of climate variability over 10,000 years
Biological material, including pollen from plants, is deposited on the land and stored for very long periods in the lake, bog, and pond sediments and, once transported downstream to the coast, in the oceans, allowing study of past climates
Have hard skeletons composed of calcium carbonate, which contains isotopes of oxygen and trace metals that have been used to determine the temperature of the water in which the coral grew, revealing the chronology of climate change
Radioactive carbon-14 is produced in the upper atmosphere by the collision of cosmic rays and nitrogen-14, with the abundance of cosmic rays varying with the number of sunspots, providing a measure of solar activity and climate change