Highlights. 1  Acute myocardial infarction is the medical name for a heart attack. 2  A number of different factors may increase your risk for a heart attack, including high blood pressure, high cholesterol, and diabetes.  Call 911 immediately if you believe you or someone you know may have had a heart attack.
The blue color of the sky is due to Rayleigh scattering. As light moves through the atmosphere, most of the longer wavelengths pass straight through. Little of the red, orange and yellow light is affected by the air. However, much of the shorter wavelength light is absorbed by the gas molecules.
The effect is much like shining a red spotlight on a white sheet. Since the Earth is spherical, the clouds at different heights turn red at different time when the sun crosses the horizon (Figure 7). Just before the sunset, the color of low clouds (e.g. stratus) will turn red first.