HRV (High Resolution Visible) satellite images capture reflected visible sunlight, providing high-detail views of cloud structures during daylight hours. The way clouds appear in these images depends largely on their optical thickness, altitude, and particle composition.

Cirrus (Ci) clouds are high-level clouds composed of ice crystals, which are optically thin and often appear as wispy or streaky formations in the sky. In HRV images, they show up as semi-transparent, filamentous streaks, often aligned with the upper-level wind direction.

In contrast:

• Nimbostratus (Ns) clouds are thick, layered, and low to mid-level. They appear as large, uniform, and dense grey areas, not semi-transparent.
• Cumulonimbus (Cb) clouds are towering and dense, often casting strong shadows and appearing very bright and solid in HRV imagery.
• Cumulus (Cu) clouds are puffy and usually lower level. They appear as bright, well-defined spots but not as streaks.