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The symbols for cloud cover on these maps, like the modern symbols, were drawn inside the circle marking the position of the weather station making the measurements. Unlike the modern symbols, these ones consisted of straight lines only rather than filled in blocks which would have been less practical on a hand drawing.
The present weather symbol depicts the current weather which normally is obstructing the visibility at the time of observation. The visibility itself is shown as a number, in statute miles in the United States and meters elsewhere, describing how far the observer can see at that time. This number is located to the left of the present weather ...
The average cloud cover of the Earth, 2005-2013. Colors range from blue (no clouds) to white (totally cloudy). [6] (click for more detail) Cloud cover values only vary by 3% from year-to-year averages, whereas the local, day-to-day variability in cloud amounts typically rises to 30% over the globe.
Also actiniform. Describing a collection of low-lying, radially structured clouds with distinct shapes (resembling leaves or wheels in satellite imagery), and typically organized in extensive mesoscale fields over marine environments. They are closely related to and sometimes considered a variant of stratocumulus clouds. actinometer A scientific instrument used to measure the heating power of ...
Stationary fronts either dissipate after several days or devolve into shear lines, but they can transform into a cold or warm front if the conditions aloft change. Stationary fronts are marked on weather maps with alternating red half-circles and blue spikes pointing opposite to each other, indicating no significant movement.
Overcast or overcast weather, as defined by the World Meteorological Organization, is the meteorological condition of clouds obscuring at least 95% of the sky. [1] However, the total cloud cover must not be entirely due to obscuring phenomena near the surface, such as fog .
Present weather symbols used on weather maps Wind barb interpretation. A station model is a symbolic illustration showing the weather occurring at a given reporting station. Meteorologists created the station model to plot a number of weather elements in a small space on weather maps.
Low-pressure areas are commonly associated with inclement weather (such as cloudy, windy, with possible rain or storms), [1] while high-pressure areas are associated with lighter winds and clear skies. [2] Winds circle anti-clockwise around lows in the northern hemisphere, and clockwise in the southern hemisphere, due to opposing Coriolis forces.