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How Do Models Make Clouds?
for more advanced readers
PREDICTING THE AMOUNT OF CLOUDS IN A GRID CELL
How can we determine the amount of clouds in a grid cell? The simplest way is to set a threshold relative humidity, for example 80%. If the grid cell's relative humidity reaches 80%, the cloud fraction goes from 0 to 100%. Obviously, it is not realistic for an area as large as a grid cell (which is typically the size of Delaware) to suddenly go from 0 clouds to completely overcast in just a few minutes. To fix this problem of "on-off" cloud activity, models can instead calculate a fraction of cloud cover that is a function of the difference between the grid cell's relative humidity and the threshold value. Next page -> how do models make clouds, continued
Links and resources
for more advanced readers
PREDICTING THE AMOUNT OF CLOUDS IN A GRID CELL
How can we determine the amount of clouds in a grid cell? The simplest way is to set a threshold relative humidity, for example 80%. If the grid cell's relative humidity reaches 80%, the cloud fraction goes from 0 to 100%. Obviously, it is not realistic for an area as large as a grid cell (which is typically the size of Delaware) to suddenly go from 0 clouds to completely overcast in just a few minutes. To fix this problem of "on-off" cloud activity, models can instead calculate a fraction of cloud cover that is a function of the difference between the grid cell's relative humidity and the threshold value. Next page -> how do models make clouds, continued
Links and resources
