The red flash of the setting sun is similar to the green flash, albeit that the red flash appears on the lower edge of the solar disk and hence never is visible as the last bit of solar disk above the horizon, like the green flash. However, the red flash can sometimes be seen clearly when the sun is near the horizon just when the sun is appearing under a sharp cloud bank. The red flash appears as a momentary small seclusion of the lower red rim of the solar disk, while the sun moves through small inversions in the atmosphere. It requires a telescope to be seen clearly.

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