Category: Wolfgang Rogge

Yosemite Park – First Visit of the Year – 2021

Although Yosemite Park is my next-door neighbor, I have not been there this year. Friedhelm suggested to visit the park. First, we stopped by some waterfall. Naturally, it’s too early to have the mighty roaring falls.

Next, we were hiking in knee-deep snow along the Merced River and trying to capture the reflection of the nearby trees in the water.

From the same location, we could see the rocky valley walls lifting up to a line of trees.

Also, the beautiful mountain top was shining in the afternoon sunlight.

Next, we went to the Horsetail waterfall. Apparently, around this time of the year, the sun, just before setting, casts the waterfall into a yellow glow. Here, an image one hour before sunset, everything looked fine, but clouds were moving in.

Well, the clouds moved in and obscured the sky. The sun went down. But, just a bit after that, the clouds broke open just a bit and the red light from the sunset illuminated the waterfall. I have not seen this phenomenon before and although it can be easily explained by physics, it surely was a magical moment. Friedhelm got the same image standing close by. Here, the Nikon version of it.

Corona Times in California

Over thirty years ago, I wrote my doctoral dissertation about tiny airborne particles. Since then, I have taught at the university level many courses about atmospheric chemistry, including aerosol formation and the fate of such tiny invisible particles.

We know that face masks work best for larger droplets. While we speak or cough, we spit out many droplets, mostly between 10 – 1000 micrometer. For comparison, a hair has a diameter of about 50 micrometer. Droplets when expelled from our mouth start vaporizing very quickly, within just a few seconds they shrink to sub-micron dimensions. At those small droplet sizes or naked corona virus size, face masks have a very low capture efficiency, in part due to the fact that those tiny droplets are highly mobile and travel by the least way of resistance, around your mask and through the gap between mask and face where tightness is limited.

Hence, it is important for EVERYBODY to wear a mask, even in public. This is especially important in winter, when droplets stay around longer, cold weather enhances survival rate of the COVID virus and UV radiation from the sun is limited. What’s the difference between accidentally flying bullets or airborne deadly viruses? Potentially, both kill.

I was recently in San Luis Obispo, a city where every 200 yards or so a poster indicates that mask wearing in public is required, yet not enforced!

What does it help when glorified individualism is valued above common sense and regard for others? A person can unknowingly be COVID positive and infecting other people. Just saying: “wear a mask if you want to protect yourself, but don’t tell me what to do” is unfortunately not very effective. Just yesterday, the COVID related death rate was over 4000 in the “Ununited States of America”. By the way, the lady in the picture is holding her mask safely in her hand.

Fortunately, there are others who care! When will mask wearing be enforced…?