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Training Guide in Surface Weather Observations - Multiple Choices

Training Guide in Surface Weather Observations - Multiple Choices

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Figure 5-10. <strong>Surface</strong>-base Layer Surround<strong>in</strong>g Station (sky hidden 4/8).<br />

5.2.2 Sky Cover with <strong>Multiple</strong> Layers<br />

The follow<strong>in</strong>g guides can be used to determ<strong>in</strong>e if multiple layers are present:<br />

a. If a ceil<strong>in</strong>g light is available, observe whether or not spots are visible at several different levels.<br />

Several well def<strong>in</strong>ed spots separated by relatively clear spaces <strong>in</strong>dicate multiple cloud layers (see<br />

Figure 5-11).<br />

b. If multiple layers are suspected, try to detect differences <strong>in</strong> direction of movement of various<br />

portions of the cloud layers. Although the absence of such differences <strong>in</strong> movement does not<br />

necessarily mean only one layer is present (s<strong>in</strong>ce the apparent cloud direction may be the same<br />

at several heights), this guide is usually reliable if the differences <strong>in</strong> height are great.<br />

c. Differences <strong>in</strong> color<strong>in</strong>g and shad<strong>in</strong>g are helpful <strong>in</strong> dist<strong>in</strong>guish<strong>in</strong>g layers. In general, lower layers<br />

tend to be darker.<br />

d. The types of clouds are also helpful <strong>in</strong> dist<strong>in</strong>guish<strong>in</strong>g multiple layers dur<strong>in</strong>g daylight.<br />

5-10

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