There are numerous cloud condensation nuclei over the North Pacific. There is always plenty of moisture in Earth’s atmosphere, but those water molecules need slightly larger, flatter surfaces to bond, accumulate, and condense into water droplets. Particles both natural (salt spray, dust, ash) and man-made (pollutants like sulfur dioxide or black carbon) can seed the formation of clouds. That is what large ships do sometimes as they cross the ocean, as shown in this March 2009 image from the MODIS instrument on the Terra satellite. The N-shaped clouds over the Pacific are what scientists call ship tracks—places where the exhaust emissions from the ships rise into the atmosphere and combine with water molecules to form linear clouds.
Nitrogen oxides, or NOx, are gases consisting of one molecule of nitrogen and varying numbers of oxygen molecules. Nitrogen oxides are produced in the emissions of vehicle exhausts and power plants. In the atmosphere, nitrogen oxides can contribute to formation of photochemical ozone (smog), can impair visibility, and have health consequences. In recent years, environmental regulations have helped reduce NOx concentrations in the United States.
Earth scientists have a lot of tools to study the planet besides visible light imagery. The near-infrared wavelengths of the spectrum help distinguish between snow and clouds or between land and water. Meanwhile, the Normalized Difference Vegetation Index (NDVI) is a measurement of how plant leaves absorb visible light and reflect infrared light. This helps scientists observe the extent and effects of drought.
The Nimbus satellites were among the first to study the Earth from space, revolutionizing our ability to predict weather.
Nor’easters are large-scale storms that can bring heavy rain, snow, and winds to the northeastern United States; the name derives from the dominant direction of the winds (northeasterlies). These low-pressure systems often take on a comma shape when viewed in satellite imagery.
And of course, there is the Nile at night, which we never tire of looking at from space.
N is also the first letter in New Year, and we wish you a happy one. Click here to see our entire satellite alphabet gallery.