500
What does a line with alternating semi-circles and triangles that face in opposite directions indicate on a weather map?
a) Warmer air is moving into the area, bringing light rain.
b) Colder air is moving under warmer air, bringing thunderstorms.
c) Faster moving cold air is overtaking the warm air and bringing heavy rain.
d) Very slow-moving warm air cannot push the existing cold air, resulting in extended periods of rain.
What is d) Very slow-moving warm air cannot push the existing cold air, resulting in extended periods of rain.