SOLID CLOUD COVER

Figure 2-41.—Determining corrected cloud elevation angle with multiple cloud layers. the band are ignored. The width of the solid band, in degrees, divided by 2 is the equipment correction for the recorder. The correction factor is applied to recorded elevation angles for all solid cloud bases and diffuse stratus bases over 45° elevation. The length of the thin marking lines is an indication of the reflected light sensed by the receiver. Line length is affected by the focus and output candlepower of each of the two lights in the RBC projector. Replacing the bulbs in the projector, cleaning a dirty projector lens, or refocusing the projector lights will change the characteristic length of the recorder marking lines; and a change in line length will require that anew equipment correction be determined. SOLID CLOUD COVER.—The cloud elevation angle of solid cloud cover, such as is indicated in figure 2-40, is read at the left edge of the solid band. The equipment correction, 2° in this case, is then added to the indicated elevation angle to find the corrected elevation angle. For solid cloud cover only, the corrected elevation angle is the same as reading the elevation angle at the center of the solid band. MULTIPLE CLOUD LAYERS.—Read the angle at the left side of the solid band, and then add the correction to obtain the proper cloud angle. For example, in figure 2-41, at time 2154Z, the solid line at 45° elevation was drawn for the left side of the solid portion of the band. The equipment correction, 2°, found from figure 2-40, is added to find the corrected angle of the cloud bases, 47°. FOG AND LOW STRATUS.—Read the elevation angle at the left side of the solid band. Do not add the correction unless the correction yields an elevation angle greater than or equal to 45°. Figure 2-42 shows a low-stratus situation that became fog on the deck at time mark 000. Between 2320Z and 2330Z, the stratus shows a solid band at 44°. Adding the equipment correction results in a corrected elevation angle of 46°, Figure 2-42.—Determining cloud elevation angles for low stratus and fog. 2-32