Views on the Forbidden City from JingShan Park. Both photos were taken in the winter but the photo on the left is, with its fog and smog filled air, more typical for the hot and humid summer. On the right the Palace covered with snow. Winters are cold, windy and dry. Snow is rare and when it snows it attracks many photographers to the JingShan, an artifical hill north of the Palace, for the beautiful views over the city.
The Beijing air quality, as measured at the compound of the US embassy, is published several times a day via Twitter.