Autumn season has begun and it is so comfortable to stay outside. As we feel the wind cool, we realize that the color of the nature surrounding us has started to change. Dn’t you feel so? Unlike the evident color changes of tinted autumnal leaves, autumn sky displays seasonal color which gradually fades.

During summer, Pacific anticyclone covers the entire sky over Japan, but as summer is over, wind direction turns over and it lets continental anticyclone take over the position. Because the amount of moisture in the air of continental anticyclone is much less, autumn sky looks clearer. We can also enjoy the different shapes of the clouds in autumn sky, which are affected by the amount of moisture in the air and the direction of the wind.

[PHOTO FROM WIKIPEDIA]
Cirrus clouds like bird feathers.

[PHOTO FROM WIKIPEDIA]
Rows of cirrocumulus clouds spread all over the sky.

[PHOTO FROM WIKIPEDIA]
Iridescent clouds: diffraction of sunshine creates a phenomenon that colors appear on the clouds. This is very rare and if you could happen to see it, you must be very lucky.

Summer is now over and we do not have to hide our body away from the strong sunshine. Why don’t we go outside and look up the beautiful autumn sky?