Thick Clouds Cast Shadows Over Mars

collarian · 24-01-08, 10:49

The last thing researchers expected to find in the red Martian skies are big, thick clouds with enough substance to cast shadows on the ground below.

Yet data collected by an instrument aboard Europe's orbiting Mars Express satellite paints just such a scene.

With an atmosphere dominated by carbon dioxide, the clouds are most likely dry ice -- frozen carbon dioxide -- that form primarily around the planet's equatorial belt due to extreme shifts in temperatures over relatively short periods of time.

For example, temperatures during warm summertime afternoons on the Martian equator can reach 65 degrees Fahrenheit, but they plunge to freezing at sunset. During the night, the temperature at the same spot could reach 100 degrees below zero.

As temperatures climb again in the morning, bubbles of warming gas rise above the surface, said French researcher Franck Montmessin with Service d'Aeronomie at the University of Versailles and the lead author of a paper about the Martian clouds in last week's Journal of Geophysical Research.

"There is potential for large-scale convection, particularly as the morning sun warms the ground," Montmessin said.

As the bubbles rise, they condense and freeze, releasing heat that boosts the gas and ice particles even higher. Eventually the clouds grow to sufficient mass to block up to 40 percent of the sun's brightness, the researchers said.

"This means that they cast quite a dense shadow and this has a noticeable effect on the local ground temperature," Montmessin said.

Cloud-shaded patches on the ground can be 50 degrees cooler than surrounding areas, the scientists found. The cold patches, in turn, can affect surface winds.

Scientists are not sure what seeds the clouds. On Earth, water vapor condenses around tiny particles of dust or salt. Mars' clouds could form around surface dust that is carried into the upper atmosphere.

Another theory is that bits of micrometeoroids are left behind to serve as cloud nuclei. Or perhaps the deed is done by tiny crystals of water ice that have been swept aloft by thermal updrafts.

The discovery of thick clouds on Mars also has researchers wondering if they could have played a role in the climate change that transformed what is believed to have been a warm and wet world into the cold, dry desert that appears to be Mars today.

**Nafass** · 24-01-08, 10:51

Ay baba az vaghti Miladoooo raft mars che khabar shod mars

Meghsi Arian jan

reshteh yadet nare

collarian · 24-01-08, 10:58

	Quote: Originally Posted by Nafass
	Ay baba az vaghti Miladoooo raft mars che khabar shod mars Meghsi Arian jan reshteh yadet nare

rafte oonja gardo khak rah endakhte

reshte na, vali sholgham shalgham foroosh

BOEING · 24-01-08, 11:24

Arezo mikonam ye rooz ensan betone az in sayare biron bere va sayarate digaro vase zendegi entekhab kone...

Merci aiarn jon kheyli jaleb bood...

**Nafass** · 24-01-08, 11:30

	Quote: Originally Posted by collarian
	rafte oonja gardo khak rah endakhte reshte na, vali sholgham shalgham foroosh

edame bahs tomorrow

akharesh man mifahmam reshtaro

miladoooo · 24-01-08, 11:44

	Quote: Originally Posted by Nafass
	Ay baba az vaghti Miladoooo raft mars che khabar shod mars Meghsi Arian jan reshteh yadet nare

hala tarjome kon plz ta bebinam che gand kari be bar avordam

24-01-08, 10:49	#1 (permalink)
collarian Neptune Join Date: Nov 2004 Location: Mars Posts: 6,867 Credits: 7,716 Thanks: 1,809 Thanked 2,516 Times in 981 Posts	Thick Clouds Cast Shadows Over Mars The last thing researchers expected to find in the red Martian skies are big, thick clouds with enough substance to cast shadows on the ground below. Yet data collected by an instrument aboard Europe's orbiting Mars Express satellite paints just such a scene. With an atmosphere dominated by carbon dioxide, the clouds are most likely dry ice -- frozen carbon dioxide -- that form primarily around the planet's equatorial belt due to extreme shifts in temperatures over relatively short periods of time. For example, temperatures during warm summertime afternoons on the Martian equator can reach 65 degrees Fahrenheit, but they plunge to freezing at sunset. During the night, the temperature at the same spot could reach 100 degrees below zero. As temperatures climb again in the morning, bubbles of warming gas rise above the surface, said French researcher Franck Montmessin with Service d'Aeronomie at the University of Versailles and the lead author of a paper about the Martian clouds in last week's Journal of Geophysical Research. "There is potential for large-scale convection, particularly as the morning sun warms the ground," Montmessin said. As the bubbles rise, they condense and freeze, releasing heat that boosts the gas and ice particles even higher. Eventually the clouds grow to sufficient mass to block up to 40 percent of the sun's brightness, the researchers said. "This means that they cast quite a dense shadow and this has a noticeable effect on the local ground temperature," Montmessin said. Cloud-shaded patches on the ground can be 50 degrees cooler than surrounding areas, the scientists found. The cold patches, in turn, can affect surface winds. Scientists are not sure what seeds the clouds. On Earth, water vapor condenses around tiny particles of dust or salt. Mars' clouds could form around surface dust that is carried into the upper atmosphere. Another theory is that bits of micrometeoroids are left behind to serve as cloud nuclei. Or perhaps the deed is done by tiny crystals of water ice that have been swept aloft by thermal updrafts. The discovery of thick clouds on Mars also has researchers wondering if they could have played a role in the climate change that transformed what is believed to have been a warm and wet world into the cold, dry desert that appears to be Mars today. __________________

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Rare pictures of Clouds	Gole_Orkide	Interesting Pictures	11	07-02-08 07:28
Very Very funny News Cast	irankhah	Must See Video Clips	2	09-01-08 21:42
shadows	Apadana	Must See Video Clips	2	26-10-07 09:54
Weird Clouds	Nafass	Interesting Pictures	3	02-09-07 08:00

24-01-08, 10:51	#2 (permalink)
Nafass Cupid Join Date: Aug 2006 Posts: 19,385 Credits: 50,689 Thanks: 7,396 Thanked 11,037 Times in 3,723 Posts	Ay baba az vaghti Miladoooo raft mars che khabar shod mars Meghsi Arian jan reshteh yadet nare

24-01-08, 11:24	#4 (permalink)
BOEING Neptune Join Date: Jul 2006 Location: Runway 08 R Posts: 7,681 Credits: 21,149 Thanks: 3,171 Thanked 1,916 Times in 982 Posts	Arezo mikonam ye rooz ensan betone az in sayare biron bere va sayarate digaro vase zendegi entekhab kone... Merci aiarn jon kheyli jaleb bood...