Question

write a summary of the current cloud cover in north america. Include date and time of the image in your report.

Answer 1

5 march 2020, 10:25 am

Clouds have long been the biggest uncertainty in climate calculations. They can both shade the Earth and trap heat. Which effect dominates depends on how reflective they are, how high they are and whether it is day or night. Things are made more complicated because cloud dynamics are complex and happen on small scales that are hard to include in the models used to predict future climate.

Cloud cover information is used alongside weather forecasts in various fields of research; however, ground observation of cloud cover is conducted by human observers, a method that is subjective and has low temporal and spatial resolutions. To address these problems, we have developed an improved algorithm to calculate cloud cover using sky image data obtained with Skyviewer equipment. The algorithm uses a variable threshold for the Red Blue Ratio (RBR), determined from the frequency distribution of the Green Blue Ratio (GBR), to calculate cloud cover more accurately than existing algorithms.

The United States satellite images displayed are infrared (IR) images.Imagery is obtained from the GOES and METEOSAT geostationary satellites, and the two US Polar Orbiter (POES) satellites. POES satellites orbit the earth 14 times each day at an altitude of approximately 520 miles (870 km). As each orbit is made the satellite can view a 1,600 mile (2,700 km) wide area of the earth. Due to the rotation of the earth the satellite is able to view every spot on earth twice each day. Data from multiple orbits are mosaicked together to provide wide scale global and full earth views in a single image. Occasional dark triangular areas that occur on POES images are a result of gaps in data transmitted from the orbiters.