How do you know something is there if you can't see it? *

We can only see things if they give off light but be we use other senses to gather information about things we cannot see.

warm front forms when a moist, warm air mass slides up and over a cold air mass. as the warm air mass rises, it condenses into a broad area of clouds. a warm front brings gentle rain or light snow, followed by warmer, milder weather.

hope i !