Postcard sky is a colloquial term for a particularly picturesque and idyllic sky view with a bright blue sky, white clouds and a generally pleasant atmosphere. The term is often used when the sky looks particularly photogenic.
Unfortunately, the postcard sky is not a summer phenomenon at all. It's not enough for it to be hot and dry. No, it takes certain weather conditions for such a sky.
White, fluffy clouds (cumulus clouds) form when the atmosphere is stable and the air is humid. They consist of water droplets or ice crystals and give the sky a dramatic and aesthetic touch.
I practically never saw any of this in the summer of 2023 in Frankfurt. Even when the sun was shining, the sky was rather white. The beautiful, deep blue was missing. One cause may be high humidity. But it was not that humid, so this was not the cause in Frankfurt. Air pollution will not have been the reason either. Even if the iPhone weather likes to emphasize that the quality of the air is supposed to be very bad.
The sun also shines behind the clouds.
White sky
It was probably much more related to the circulation in the atmosphere. We had certain weather patterns that lead to stable stratification of the air. This stratification can prevent the air in the atmosphere from being well mixed. This allows air pollutants and particles that would normally be distributed in higher layers to become trapped near the Earth's surface and scatter sunlight. This results in a cloudy, white sky.
There's no point in getting upset about the weather. It won't change anyway.
I am not a meteorologist and yet I deal with this topic. Because the white sky provides a different light. Due to the many particles in the sky, the light is more scattered before it reaches the ground.
With a white sky, the light conditions are often softer and more even because the scattered light comes from different directions. As a result, the shadows are less pronounced and the environment appears brighter overall.