To rotate the globe you can either click and hold your mouse on the image and drag in whichever direction you wish, or you can use the arrow keys on the keyboard to navigate the globe. Background: NASA’s Total Ozone Mapping Spectrometer (TOMS) provides measurements that enable scientists to accurately estimate how much of the sun’s UV-B (290 to 320 nm) radiation reaches the Earth’s surface. Too much exposure to these wavelengths causes sunburn in human skin. The false-color image above is a global map, averaged from TOMS snapshots collected every day over a one-month period, showing where more or less UV radiation reaches the surface. Yellow pixels show the highest levels of radiation at the surface, red and pink hues are intermediate values, and white indicates little or no UV exposure. The TOMS sensor flies in a polar orbit, crossing the equator every day at 12 noon local time, allowing it to measure the total amount of ozone in a column of atmosphere as well as cloud cover over the entire globe. Ozone and clouds absorb most of the ultraviolet light passing through the atmosphere. TOMS also measures the amount of solar radiation escaping from the top of the atmosphere. It is the combination of those three measurements that enables scientists to accurately estimate the amount of UV radiation that reaches the Earth’s surface. Ozone gas in the stratosphere (upper atmosphere) absorbs ultraviolet light, thus protecting living things from the sun’s harmful ultraviolet radiation. Man-made chemicals and weather conditions over Antarctica combine to deplete stratospheric ozone concentrations during the winter months there. Data courtesy TOMS science team, NASA Goddard Space Flight Center Questions: What is the relationship between UV radiation exposure at the surface and levels of ozone in the stratosphere?     In general, where is UV radiation exposure the greatest?     What are some of the consequences of increased UV radiation exposure?     Links: Ozone (http://Earthobservatory.nasa.gov/Library/Ozone/)   UV Radiation: How it Affects Life on Earth (http://earthobservatory.nasa.gov/Library/UVB/)   On the Trail of the Missing Ozone (http://www.epa.gov/ozone/science/missoz/index.html)   next activity (#1): Comparing ozone levels in October 1979 to those in October 2000 previous activity (#11): Comparing vegetation to landcover classification from January to December 1998

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