Saturday, 15 February 2014
The Martian Atmosphere Must be Thicker Than We've been Told
According to the text books Mars has very low surface air pressure which is 0.6 of the sea level pressure we have on Earth. The pounds per square inch is 0.087 (psi) to our 14.69 (psi). Images of the Martian sky taken in these alleged conditions often reveal an orange or grey-blue sky.
At 0.087 psi the level of Martian air pressure is similar to the very thin atmosphere on Earth at an altitude of 100,000 feet. According to this chart the psi on Earth at 100,000 feet is 0.162 compared to Mars at 0.087.
HOWEVER, the problem we face is that during the daylight hours on Earth at 100,000 feet the sky appears black.
On Mars, with a similar air pressure, looking upwards we are not treated to a black sky during the daylight hours but something either reddish or blue-grey.
We have been *told* that the colour of the Martian sky is due to dust particles suspended in the atmosphere.
BUT without dust, or even with small amounts of dust, and having such a thin atmosphere, the sky should conform to the same physical principles we find on Earth - the sky will be black.
On Earth, if we find ourselves looking skyward at a reddish hue we need either a lot of dust, like what one sees during a dust storm (in which visibility becomes obstructed); or instances where the Sun is shining low in the sky (through a lot more atmosphere) and the Rayleigh light scattering effect has turned away the blue wavelengths of light leaving the longer wavelengths of light (such as red) to travel in the direction of the observer. Also causing the red colouring on Earth is the Mei light scattering effect that interacts with larger sized particles (dust) at lower altitudes to cause red sunset colours to dominate out of the Sun's spectrum of light.
The problem we face with Mars is that there is an allegedly thin atmosphere and a distinct lack of haze from dust in the sky - except when there are dust storms. Looking at the thousands of high resolution images taken of Mars by the European Space Agency probe Mars Express you can see pictures without noticeable dust haze. Many of the pictures are stunning because of their clarity.
If the atmosphere was always full of dust - enough to cause a red hue- then we should almost always see instances of dust haze, just like on Earth when we find orange sky situations.
One should note that on any Earth day there is actually dust suspended in our relatively thick atmosphere - car filters pick it up all the time - and yet looking upwards - we see no red hues. All we are greeted with is the blue glare from the Rayleigh effect as white light interacts with small gas molecules in our atmosphere.
At night time, we still have our atmosphere, with the dust, and yet when we look up, there is no red hue, even when we have the stronger levels of light reflected directly off the Moon, absent the excessive blue glare from the daytime Rayleigh effect. Looking at the Moon we commonly see the white Sun light, and the grey and darker surface colours, being reflecting off the Moon - plus occasionally we see it as yellow thanks to mild Rayleigh scattering and dust effects - but no reds like in the Mars pictures.
With such a thin atmosphere on Mars, the sky should be predominantly black, just like on Earth at 100,000 feet, with occasional instances of redness from dust storms. The idea that there is enough dust always suspended in the thin Martian atmosphere to give a constant red hue seems extremely unlikely.
It has also been claimed that the red Mars we see, that looks like a star in the night sky, is due again to suspended dust in the atmosphere - in combination with the planet's surface colour. Yet when we look at the Moon we see its colour does not come from dust suspended in an atmosphere, but from the dark surface, the Sun's white light, and the effects of our own atmosphere. The same can hold true of Mars and we should not automatically accept that dust in the atmosphere must be the primary element - although such an effect is present when there are dust storms, which is to be expected on a planet that comprises mostly of desert.
The bottom line is that according to the official account - with a thin atmosphere - the Martian sky should theoretically be very black. There is no evidence to show that there is enough dust continually suspended in the clear sky to create the haze needed to produce an orange sky we see in the official pictures - the ones labelled as showing the true Martian sky colour.
The same process we find Earth works on Mars - the basic physics does not change.
What is more likely, is that the sky we see in the Martian pictures is much thicker than what we have been told.
This thicker atmosphere would account for 'wash features' on the surface plus many of the images we find with blue-grey sky colours. The orange clear sky colours would be the image 'enhanced' pictures released by NASA, not the true colour pictures. At present many scientists are having trouble explaining the liquid water related phenomena (http://rt.com/news/water-flowing-mars-nasa-evidence-470/) because water would evaporate rapidly in the officially endorsed low pressure environment.
[Posted at the SpookyWeather blog, February 15th, 2014.]