Thanks Ed and Frank.
I had a look on Mars yesterday evening with a window of 2 hours.
In first, looking at Mars with naked eyes, it appeared also yellowish and not the orange-red usual color.
I used the 254mm cassegrain for the report performed at 238x, more was not possible (the 312x too blurring with the seeing). The overall disk color was not usual and I confirm my observations of the 3rd with some adds, considering the observation in IL.
Generally, for all channel color observed, especially the red, the contrast levels are poor. Mare around Solis Lacus, Aonius, Sirenum were almost un-perceptible. Mare Boreum around the cap was not conspiscious. All the half tones features represented on the temperate area looked very low contrasted, Nikokeras and surroundings too, Elysium at the limb whitish with dark boundaries looked also low contrasted (seemed reinforced by the transition white dark boundaries, etc...
The best views were under the blue filter (relatively), and exceptionally poor in contrast under the red filter, the yellow at a lesser intensity.
Indeed the sketches seems to show hard contrasts, enhanced here for showing the difference between colors.
I remembered the vision of Syrtis Major during the great dust storm where it disappeared almost. I saw it in spite of in the 100mm refractor when its contrast was around 3% only. This was near a limit. Here on the 7th May, yesterday, we can attribute a level contrast of the features staying on the temperates zones to be say 5% more or less.
I we try to attribute a density of atmosphere attenuation, this could be minimum 50% (those features under clear atmosphere turn around 10% level). The tendency, stronger in red color surely.
Therefore in addition to the white hazze we see due to season occurences, there is an amount of dust with a non-negligeable density.
This is a fact.
Where is coming this dust:
- cap thawing speed very high, sothat dust are transported by the white hazze,
- deep white clouds at equator limbs crearing strong convections from the ground (we saw in yellow-red colors patches of bright ground area when white clouds disappeared).
Interresting to follow.
Yes Ed I confirm your observationnal points.
Thanks for your post.