The correct option is 1 and 3 only.
Explanation
Thunderstorms are intense, short-duration, local weather phenomena characterized by strong vertical air currents, lightning, thunder, and heavy precipitation. They typically develop in unstable atmospheric conditions.
Statement 1 is Correct:
Thunderstorms are primarily caused by intense convection. On hot and moist days, the ground heats up significantly, causing the adjacent air to warm, expand, and rise rapidly. This rapid ascent of moist air leads to instability and the formation of storm systems.
Statement 2 is Incorrect:
A thunderstorm is structurally defined by a well-grown Cumulonimbus cloud. These clouds have immense vertical development, often reaching the tropopause and resembling an anvil or cauliflower. In contrast, Stratus clouds are layered, horizontal clouds associated with stable air and steady, light precipitation, not violent storms.
Statement 3 is Correct:
Thunderstorms are capable of producing hailstorms. The strong updrafts within a Cumulonimbus cloud can push water droplets above the freezing level. These droplets freeze into ice pellets and circulate within the cloud, accumulating layers of ice until they become too heavy for the updrafts to support, falling to the ground as hail.
Key Takeaway:
Thunderstorms are generated by strong convection currents and are exclusively associated with Cumulonimbus clouds, which can produce lightning, thunder, heavy rain, and hail.