UNIT 10—LESSON 2
OVERVIEW Identify cloud patterns
seen in satellite imagery.
OUTLINE Mesoscale cloud patterns CLOUD INTERPRETATION Since man was first confronted with chang-ing
Mesoscale cloud patterns
Since man was first confronted with chang-ingweather, he looked to the skies to foretell future changes. Clouds were one of the first signs used. Clouds were eventually classified according to genera, species, and varieties to help us better understand weather patterns. Over the last 20 years, weather satellites have looked earthward providing us with a different perspective of these features. Meteorologists have studied satellite imagery to interpret cloud types and patterns as viewed from space. The following text will discuss their findings on mesoscale cloud patterns, cloud types, subsynoptic- and synoptic-scale cloud features, and Earth’s surface features as viewed in satellite imagery.
MESOSCALE CLOUD PATTERNS
Mesoscale cloud patterns and types have ahorizontal extent of approximately 1 to 100 kilometers.
Learning Objective: Identify and differ-entiatebetween the cloud patterns and types of clouds seen in satellite imagery.
Cloud elements are the smallest distinguishableunits in a cloud mass or pattern as seen in imagery.
A cloud street is a series of aligned individual "elements" that are not interconnected. Cloud streets may be curved or straight and are usually equidistantly spaced. Figure 10-2-1 shows cloud streets and the cloud elements that compose them.
A cloud line is much like a cloud street exceptthe elements are connected and have a general width of less than 1 degree of latitude. Cloud lines are most predominant over tropical oceans, but are observed at all latitudes. They provide a good indication of the surface and low-level wind direc-tions over an area, since they normally parallel these winds. Where cloud lines run parallel to each other over long distances, constant wind directions exist in the lower atmosphere. Figure 10-2-2 shows cloud lines formed in maritime tropical air advected into the south central United States.
A cloud band is a formation of clouds witha distinct long axis where the ratio of length to width is at least 4 to 1. Cloud bands may or may not be associated with fronts.