Which characteristic helps distinguish cirrostratus clouds from altostratus clouds?

Cirrostratus clouds and altostratus clouds can indeed be distinguished by the presence of halos around the sun or moon, which is a characteristic feature of cirrostratus clouds. Cirrostratus clouds are composed of ice crystals due to their high altitude, and when sunlight or moonlight passes through these crystals, it can create the appearance of halos, which are rings of light that surround the sun or moon.

In contrast, altostratus clouds, which exist at a lower altitude and are typically composed of water droplets, do not generate halos. They can sometimes obscure the sun but do not have the same effect due to the difference in their composition and structure. This distinction is crucial for meteorologists and weather enthusiasts alike, as it provides visual clues to the type of weather conditions present and helps in forecasting.

This clarity in how halos form purely due to the ice crystals in cirrostratus clouds is key in identifying them, setting them apart from altostratus clouds based on this specific characteristic.