Ever wonder what the global weather forecast for the Earth might be? Just take a look at a new composite image of Earth’s cloud patterns. NASA created this map by compiling data mined from satellite images for more than a decade.
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This newly composited data reveals that the forecast for Earth is mostly cloudy. More specifically, about 67 percent of the Earth tends to be covered by clouds. NASA’s Aqua satellite, which is charged with collecting information regarding the facets of our planet’s water cycles, shows where clouds tend to always be present.
The Aqua satellite houses MODIS, which stands for Moderate Resolution Imaging Spectroradiometer. The MODIS technology provides full images of the earth every 1 to 2 days allowing scientists to get a pretty good picture of what is happening weather-wise on the planet.
In a new study, instead of just looking at the data from one day, scientists examined the findings obtained from 2002 to 2015. Using this information, they could get a better picture of global weather patterns over time by averaging the locations of clouds thereby creating the new cloud map.
The findings from this map show that three zones on Earth tend to be particularly cloudy. One zone is located in a strip at the equator, and the other two are located in bands in the mid-latitudes, 60 degrees north and south of the equator respectively.
Why do these cloud bands persistently exist in these locations? NASA’s Earth Observatory explains how Hadley cells and Ferrel cells work to contribute to these bands of cloud cover. Regarding the overcast equatorial band, NASA explains, “Hadley cells are defined by cool air sinking near the 30 degree latitude line north and south of the equator and warm air rising near the equator where winds from separate Hadley cells converge. As warm, moist air converges at lower altitudes near the equator, it rises and cools and therefore can hold less moisture. This causes water vapor to condense into cloud particles and produces a dependable band of thunderstorms in an area known as the Inter Tropical Convergence Zone (ITCZ).”
Regarding the two bands above and below the equator, NASA clarifies, “This is where the edges of polar and mid-latitude (or Ferrel) circulation cells collide and push air upward, fueling the formation of the large-scale frontal systems that dominate weather patterns in the mid-latitudes.”
In addition to these three cloud bands, another cloud pattern is visible on the new map, as indicated by lighter areas on the west coasts of certain continents. NASA notes that ocean currents, along with other ocean behaviors, contribute to the cloudiness on the western sides of North America, South America and Africa.
NASA’s Earth Observatory offers a disclaimer, however, about their beautiful new blue map, reminding onlookers that the image represents an average of cloudiness from a “top-down” view of the earth as seen from the Aqua satellite. It does not represent a day-to-day look at the weather on Earth.
So, if you need to know if it is cloudy where you are, perhaps the best thing to do is step outside and look.