This spectacular image of the Mall area was acquired on Saturday, April 1, 2000 by Space Imagings IKONOS sensor. Here we are moving across the Mall, from west to east and we will pause over the Capitol Building. Lets just sit back for a few seconds and enjoy the view. We will then gradually pull back from this highly localized view from space, to obtain a more regional perspective provided by Landsat 7. This regional view permits us to follow the entire length of the Potomac River, from its headwaters in the Shenandoah's, until it flows into the Chesapeake Bay. We can also see the full extent of the Chesapeake and Delaware Bays as they flow into the Atlantic. We will continue to pull back farther to obtain more continental and global views of the Earth as provided by a new instrument known as MODIS, or the Moderate Resolution Imaging Spectroradiometer, the primary instrument on the Terra spacecraft. Finally, we rotate the Earth so as to see a representation of the Earths stable light sources, as derived from DMSP satellites. (Note: This animation is a precursor to the Great Zooms. It is based on the same concept and data sources, but is somewhat less polished, particularly in the area of color matching.)

This is what the Earth looks like at night. Can you find your favorite country or city? Surprisingly, city lights make this task quite possible. Human-made lights highlight particularly developed or populated areas of the Earths surface, including the seaboards of Europe, the eastern United States, and Japan. Many large cities are located near rivers or oceans so that they can exchange goods cheaply by boat. Particularly dark areas include the central parts of South America, Africa, Asia, and Australia. The above image is actually a composite of hundreds of pictures made by the Defense Meteorological Satellite Program (DMSP) currently operates four satellites carrying the Operational Linescan System (OLS) in low-altitude polar orbits. Three of these satellites record nighttime data. The DMSP-OLS has a unique capability to detect low levels of visible-near infrared (VNIR) radiance at night. With the OLS VIS band data it is possible to detect clouds illuminated by moonlight, plus lights from cities, towns, industrial sites, gas flares, and ephemeral events such as fires and lightning-illuminated clouds. The Nighttime Lights of the World data set is compiled from the October 1994 - March 1995 DMSP nighttime data collected when moonlight was low. Using the OLS thermal infrared band, areas containing clouds were removed and the remaining area used in the time series. This animation is derived from an image created by Craig Mayhew and Robert Simmon from data provided by Christopher Elvidge of the NOAA National Geophysical Data Center.

The Lights of Earth can be seen from space. Human-made lights highlight particularly developed or populated areas of the Earths surface, including the seaboards of Europe, the eastern United States, and Japan. Many large cities are located near rivers or oceans so that they can exchange goods cheaply by boat. Particularly dark areas include the central parts of South America, Africa, Asia, and Australia. The above image is actually a composite of hundreds of pictures made by the Defense Meteorological Satellite Program (DMSP) currently operates four satellites carrying the Operational Linescan System (OLS) in low-altitude polar orbits. Three of these satellites record nighttime data. The DMSP-OLS has a unique capability to detect low levels of visible-near infrared (VNIR) radiance at night. With the OLS VIS band data it is possible to detect clouds illuminated by moonlight, plus lights from cities, towns, industrial sites, gas flares, and ephemeral events such as fires and lightning-illuminated clouds. The Nighttime Lights of the World data set is compiled from the October 1994 - March 1995 DMSP nighttime data collected when moonlight was low. Using the OLS thermal infrared band, areas containing clouds were removed and the remaining area used in the time series.

The Lights of Earth can be seen from space. Human-made lights highlight particularly developed or populated areas of the Earths surface, including the seaboards of Europe, the eastern United States, and Japan. Many large cities are located near rivers or oceans so that they can exchange goods cheaply by boat. Particularly dark areas include the central parts of South America, Africa, Asia, and Australia. The above image is actually a composite of hundreds of pictures made by the Defense Meteorological Satellite Program (DMSP) currently operates four satellites carrying the Operational Linescan System (OLS) in low-altitude polar orbits. Three of these satellites record nighttime data. The DMSP-OLS has a unique capability to detect low levels of visible-near infrared (VNIR) radiance at night. With the OLS VIS band data it is possible to detect clouds illuminated by moonlight, plus lights from cities, towns, industrial sites, gas flares, and ephemeral events such as fires and lightning-illuminated clouds. The Nighttime Lights of the World data set is compiled from the October 1994 - March 1995 DMSP nighttime data collected when moonlight was low. Using the OLS thermal infrared band, areas containing clouds were removed and the remaining area used in the time series.

Nitrogen dioxide, NO2, is a traffic-related pollutant. Emissions are generally highest in urban rather than rural areas. Annual mean concentrations of nitrogen dioxide in urban areas are generally in the range 10-45 ppb, and lower in rural areas. Levels vary significantly throughout the day, with peaks generally occurring twice daily as a consequence of rush hour traffic. Concentrations can be as high as 200 ppb. Particulate matter is very fine and can be carried deep into the lungs where they can cause inflammation and a worsening of the condition of people with heart and lung disease. Further, the problem is not necessarily concentrated in the inner cities. Because many major road - motorway interchange complexes are situated in semi-rural areas, under conditions of near-stationary traffic, a rapid build-up of engine exhaust pollution can occur, which if the low-level atmospheric conditions are correct, will not be dispersed.