Category Archives: Phenomena

Why is lightning white?

Lightning is a huge electrical discharge.

Static charges form in a storm composed of ice crystals and liquid water drops. Turbulent winds inside the storm cause particles to rub against one another, causing electrons to be stripped off, making the particles either negatively or positively charged. Continue reading

Category: Meteorology, Phenomena, Severe Weather

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Why is the sky blue?

All the attention of today’s eclipse has raised interest in the sky’s color.

To understand why the sky is blue, we need to understand a little about light. Light is a form of electromagnetic energy. This form of energy does not need matter to propagate. Continue reading

Category: Meteorology, Phenomena

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Why does the shadow of an eclipse travel west to east?

The sun appears to rise in the east and set in the west. This happens because of how the Earth spins as it orbits the sun. If you are in space and look down on the North Pole, the Earth … Continue reading

Category: Phenomena

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What causes a double rainbow?

The classic rainbow is a single, bright, colored arc. Red is the outermost color of this arc, and violet is always the innermost color.

On occasion, you may have seen two rainbows at once. The lower rainbow is the primary rainbow and the higher, fainter, colored arc is the secondary rainbow. The color sequence of the secondary rainbow is opposite to the primary; red is on the inside of the arc and violet on the outside. Continue reading

Category: Meteorology, Phenomena

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What is a derecho?

A derecho (pronounced deh-RAY-cho, a Spanish word meaning “straight ahead”) is an hours-long windstorm associated with a line of severe thunderstorms.

It is a result of straight-line winds, not the rotary winds of a tornado — hence its name. Derechos in the United States are most common in the late spring and summer (May through August). Continue reading

Category: Meteorology, Phenomena, Severe Weather

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