Adense mix of dry, hot rock fragments and hot gas erupting from volcanic vents at high speed is

Pyroclastic Flow

Explanation:

A pyroclastic flow ( also known as a pyroclastic density current or a pyroclastic cloud) is a fast-moving current of hot gas and volcanic matter (collectively known as tephra) that moves away from a volcano about 100 km/h (62 mph) on average but is capable of reaching speeds up to 700 km/h (430 mph).

A. pyroclastic flow

Explanation: hope it helps ^w^

weather forecasts are done by collecting data about the current state of the atmosphere mainly the temperature, humidity and wind and using meteorology, to determine the atmosphere that evolves over time. the h and l mean the high and low pressure. the red strip is a warm front. the blue strip is a cold front. the blue and red strip is a stationary front. the purple strip is a occluded front.

explanation:

the higher the current the higher the mag field around it the higher the influence on the compass