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Andes Effect

Peter Dexter

Well-known member
This is a late afternoon view of the eastern slope of the Western Cordillera of the Andes. The Pacific ocean lies on the other side of these clouds. Every day winds from the west blow clouds eastward over the ocean until they encounter the western slope of the Andes at which point they are forced up into much colder air. As a result they condense and produce rain on the western side but as they crest the cordillera they enter a rain shadow over the high and dry valley of Cauca. This cloud build up at the crest is a daily afternoon event that I get to view as I drive up the mountain towards home from the city of Cali.


19766349808_2034fa6557_b.jpg
 

Asher Kelman

OPF Owner/Editor-in-Chief
This is a late afternoon view of the eastern slope of the Western Cordillera of the Andes. The Pacific ocean lies on the other side of these clouds. Every day winds from the west blow clouds eastward over the ocean until they encounter the western slope of the Andes at which point they are forced up into much colder air. As a result they condense and produce rain on the western side but as they crest the cordillera they enter a rain shadow over the high and dry valley of Cauca. This cloud build up at the crest is a daily afternoon event that I get to view as I drive up the mountain towards home from the city of Cali.


19766349808_2034fa6557_b.jpg

So the clouds "empty of rain as the cross the mountains. But is the rain shadow because most all the water is already dropped, or because it meets hot air and then the remaining water in the cloud is kept evaporated and cannot condense?

In any case it's awesome.

Another question, are there raptors that ride on these air movements to hunt the creatures that must flourish on the lush western side of the Andes?

Asher
 

Doug Kerr

Well-known member
Hi, Peter,
This is a late afternoon view of the eastern slope of the Western Cordillera of the Andes. The Pacific ocean lies on the other side of these clouds. Every day winds from the west blow clouds eastward over the ocean until they encounter the western slope of the Andes at which point they are forced up into much colder air. As a result they condense and produce rain on the western side but as they crest the cordillera they enter a rain shadow over the high and dry valley of Cauca. This cloud build up at the crest is a daily afternoon event that I get to view as I drive up the mountain towards home from the city of Cali.


19766349808_2034fa6557_b.jpg

Beautiful shot, and a very nice explanation the meteorological phenomenon at work.

Here in New Mexico, the air is much drier. As the air is blown eastward by the prevailing winds, when it encounters a mountain range it is compressed and warms, but the heat is soon dissipated, and the air temperature remains moderate.

Then, as the air crosses the mountain crest, it expands quickly and thus cools dramatically. This then condenses the modest amount of moisture in the air, which falls as rain or snow, depending on the overall temperature context, on the eastward flank of the mountains.

Which is why in Mew Mexico I always have lived against the westward flank of a mountain range!

Best regards,

Doug
 
Last edited:

Asher Kelman

OPF Owner/Editor-in-Chief
.......

Then, as the air crosses the mountain crest, it expands quickly and thus cools dramatically. This then condenses the modest amount of moisture in the air, which falls as rain or snow, depending on the overall temperature context, on the eastward flank of the mountains.

Which is why in Mew Mexico I always have lived against the westward flank of a mountain range!

Doug,

There must be more wild life and flowers on the Eastern side of the mountains. So wouldn't that be more pleasant. For me it would be more "British" as opposed to hot and arid!

Asher
 

Peter Dexter

Well-known member
Asher that is a good question but I think the answer is a bit of both. As to raptors there are many species but I don't what the distribution is.
 

Doug Kerr

Well-known member
Hi, Asher,

Doug,

There must be more wild life and flowers on the Eastern side of the mountains.

Oh, yes.

So wouldn't that be more pleasant. For me it would be more "British" as opposed to hot and arid!

Well, some people like that "temperate zone" environment better than the "high desert" environment. But we don't.

It's why the German Air Force has their advanced tactical flying school here in Alamogordo rather than in Germany, with its "British" weather! And why many of the German airmen, whether having been here as part of the school faculty or as students, when they retire from the Luftwaffe, move here.

But when we drive through the eastern slope of the Sacramentos (usually on our way out of state) we enjoy the picturesque almost Switzerland-looking countryside.

We actually had a "British weather" day on New Year's Day (got 2% of our expected annual rainfall that day - 0.24 inches!), but I have recovered from it.

Best regards,

Doug
 

Asher Kelman

OPF Owner/Editor-in-Chief
Well Doug,

I much prefer seeing lush green than parched desert and bare rocks!

Also there's wildlife!

Asher
 

Doug Kerr

Well-known member
Hi, Asher,

Well Doug,

I much prefer seeing lush green than parched desert and bare rocks!

A chacun son égout

We have desert in the back yard and rocks (crushed) in the front. The nice thing both is that you don't have to water it or mow it!!

Also there's wildlife!

Not much of that in Alamogordo - in fact, the town nearly shuts down about 10:00 pm except for the Walmart and the big grocery stores.

And coyote do not stroll down Thunder Road in the evening like they used to.

Best regards,

Doug
 

Peter Dexter

Well-known member
If I had stayed in the states after I retired I probably would have gone to Tucson (from Missouri) in order to always be a short drive from the Sonoran desert. I've spent a lot of quality time backpacking in the Organ Pipe National Monument and a little further south in the Pinicate in Mexico.If I ever go back to the states that's where I'd want to go.
 

Doug Kerr

Well-known member
Hi, Peter,

If I had stayed in the states after I retired I probably would have gone to Tucson (from Missouri) in order to always be a short drive from the Sonoran desert. I've spent a lot of quality time backpacking in the Organ Pipe National Monument and a little further south in the Pinicate in Mexico.If I ever go back to the states that's where I'd want to go.

Sounds good.

It is interesting that we now have two National Monuments with "Organ" in their names, the Organ Pipe Cactus National Monument in southern Arizona, to which I think you were referring, and the Organ Mountains-Desert Peaks National Monument, established in 2014, located just east of Las Cruces, New Mexico, in the Chihuahuan Desert.

The Organ Mountains get their name from the striking organ-pipe-like appearance of the granite "needles" that form a major section of the range.

There are today both climbing routes and hiking trails in the Organ Mountains. There is a very nice recreation area, accessible by car, in the eastern foothills of the range, with picnic facilities and the like. Carla took her Red Hat Society chapter there for an adventure a year or so ago.

And next week she will drive to Tucson (about a 5.5 hour drive from here in Alamogordo, N.M.) to attend a special Red Hat Society event.

Best regards,

Doug
 

Doug Kerr

Well-known member
Hi, Jerome,

You may want to read that Wikipedia article about the phenomenon:

Rainshadow_copy.jpg

Thanks for that.

That is not what we have here. The phenomenon we have hear results in substantial rain (relatively!) on the entire leeward slope, and much less on the windward slope.

"Egout" means "sewer" . . .

Yes. It is a joke, non?

. . . you may think about "goût", which means "taste".

I often do.

Best regards,

Doug
 

Jerome Marot

Well-known member
That is not what we have here. The phenomenon we have hear results in substantial rain (relatively!) on the entire leeward slope, and much less on the windward slope.

Alamogordo seems to be flanked by two north-south mountainous chains, San Andres on the west and Mescalero on the east. Indeed, there is vegetation on the eastern side of these mountains, meaning it rains more on the east than on the west.

The reason, I think, is that the western side is flanked by a huge mountain system in Arizona, so that any wind from the west would have shed its water already. On the other hand, when wind blows from the east (which apparently is the case as I am writing), the air passing above the Texas plains would still have a bit of humidity which it would shed on these mountains. Consistent with that theory is the idea that there is more vegetation (and hence probably more rain) in Mescalero than in San Andres.
 

Doug Kerr

Well-known member
Hi, Jerome,

Alamogordo seems to be flanked by two north-south mountainous chains, San Andres on the west and Mescalero on the east.

Actually, to the east of Alamogordo are the Sacramento mountains.

I think the Mescalero Mountains are farther north, I think a subrange of the Sierra Blanca mountain chain. (I know somebody who is very familiar with that area; I'll ask her to get me straightened out about that.)

Indeed, there is vegetation on the eastern side of these mountains, meaning it rains more on the east than on the west.

Quite so. This is more prominent on the eastern slope of the Sacramentos than on the eastern slope of the San Andres. [Oh, I see you cover that in your comments to follow!)

The reason, I think, is that the western side is flanked by a huge mountain system in Arizona, so that any wind from the west would have shed its water already. On the other hand, when wind blows from the east (which apparently is the case as I am writing), the air passing above the Texas plains would still have a bit of humidity which it would shed on these mountains. Consistent with that theory is the idea that there is more vegetation (and hence probably more rain) in Mescalero than in San Andres.

That may very well be the explanation.

Thanks for those thoughts.

Best regards,

Doug
 
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