A place for my geography-geek side to let loose.

My regular page is: solipsismnow.tumblr.com

 

earthstory:

It looks like free flowing lava doesn’t it?  It’s not – it’s just plain ole water! This waterfall, known as horsetail fall, flows over the sheer granite face of El Capitan in Yosemite National Park, California. Horsetail is the longest free-falling falls in the park, with a drop of 1,500 feet before it hits granite and spills another 500. The falls however are most famous for the phenomenon shown in this photo. At sunset in mid-February as a result of celestial configuration and cooperative winter weather, the water cascading from the high open cliff face is saturated with a golden glow, resembling fire! This was first recorded by outdoor photographer Galen Rowell in 1973 and since, luckily for those who have never witnessed it; many photographers have now captured this amazing spectacle, on camera and on film.  Photographing this beautiful sight requires the application of astronomy, physics and geometry as hopefuls consider the azimuth degrees and minutes of the earth’s orbit relative to the sun to determine the optimal day to experience it. They are looking for the lowest angle of light that will paint Horsetail the colours of an iridescent sunset as rays reflect off granite behind the water. It materializes in varying degrees of intensity for the same two weeks every year. Amazing – Nature is awesome. -Jean Photo courtesy of Jennifer Durham

earthstory:

It looks like free flowing lava doesn’t it?

It’s not – it’s just plain ole water!

This waterfall, known as horsetail fall, flows over the sheer granite face of El Capitan in Yosemite National Park, California. Horsetail is the longest free-falling falls in the park, with a drop of 1,500 feet before it hits granite and spills another 500. The falls however are most famous for the phenomenon shown in this photo. At sunset in mid-February as a result of celestial configuration and cooperative winter weather, the water cascading from the high open cliff face is saturated with a golden glow, resembling fire!

This was first recorded by outdoor photographer Galen Rowell in 1973 and since, luckily for those who have never witnessed it; many photographers have now captured this amazing spectacle, on camera and on film.

Photographing this beautiful sight requires the application of astronomy, physics and geometry as hopefuls consider the azimuth degrees and minutes of the earth’s orbit relative to the sun to determine the optimal day to experience it. They are looking for the lowest angle of light that will paint Horsetail the colours of an iridescent sunset as rays reflect off granite behind the water. It materializes in varying degrees of intensity for the same two weeks every year.

Amazing – Nature is awesome.

-Jean

Photo courtesy of Jennifer Durham

earthstory:

Neanderthal had low genetic diversityFollowing on from a recent post about how much of our cousin’s genetic legacy lives on in us (seehttp://tinyurl.com/mzm2h3e), another study just published in Proceedings of the National Academy of Sciences has compared over 17,000 known protein coding genes between 3 specimens excavated in Croatia, Siberia and Spain in order to assess something of the genetic variation between these widely dispersed populations.Comparing these with the average human spread, Neanderthal had very low diversity, and the results suggest low populations living in small, relatively isolated groups. They had about a quarter of the rate of African diversity, and a third of that of Asians or Europeans. Compared to ancestral humans, the genes linked to skeletal morphology (think of those huge thick bones) changed to a greater extent during their evolution than ours, while modern humans who swiftly became more geographically diverse show greater development in genes affecting skin pigmentation, demonstrating the effect of selective pressures of the different environments we evolved in.Recent research suggests that we spread out of Africa in more than one wave, starting as early as 140,000 years ago and that each wave has its own distinctive genetic legacy, partly influenced by the environment they ended up in. The two lineages split sometime between 750 and 550,000 years ago, and we were at the limit of diverging into two species when non African Homo sapiens interbred with our cousins some 40,000 years back. Humans are already less diverse than apes, suggesting genetic bottlenecks in our deep past, and Neanderthal seems to have been even less diverse, possibly as a result of repeated ice age population squeezes.LozImage credit: Aquila Gibhttp://www.livescience.com/44989-neanderthals-had-shallow-gene-pool.htmlhttp://phys.org/news/2014-04-genetic-neanderthals-diverse-modern-humans.htmlOriginal paper, paywall access: http://www.pnas.org/content/early/2014/04/16/1405138111

earthstory:

Neanderthal had low genetic diversity

Following on from a recent post about how much of our cousin’s genetic legacy lives on in us (seehttp://tinyurl.com/mzm2h3e), another study just published in Proceedings of the National Academy of Sciences has compared over 17,000 known protein coding genes between 3 specimens excavated in Croatia, Siberia and Spain in order to assess something of the genetic variation between these widely dispersed populations.

Comparing these with the average human spread, Neanderthal had very low diversity, and the results suggest low populations living in small, relatively isolated groups. They had about a quarter of the rate of African diversity, and a third of that of Asians or Europeans. Compared to ancestral humans, the genes linked to skeletal morphology (think of those huge thick bones) changed to a greater extent during their evolution than ours, while modern humans who swiftly became more geographically diverse show greater development in genes affecting skin pigmentation, demonstrating the effect of selective pressures of the different environments we evolved in.

Recent research suggests that we spread out of Africa in more than one wave, starting as early as 140,000 years ago and that each wave has its own distinctive genetic legacy, partly influenced by the environment they ended up in. The two lineages split sometime between 750 and 550,000 years ago, and we were at the limit of diverging into two species when non African Homo sapiens interbred with our cousins some 40,000 years back. Humans are already less diverse than apes, suggesting genetic bottlenecks in our deep past, and Neanderthal seems to have been even less diverse, possibly as a result of repeated ice age population squeezes.

Loz

Image credit: Aquila Gib

http://www.livescience.com/44989-neanderthals-had-shallow-gene-pool.html
http://phys.org/news/2014-04-genetic-neanderthals-diverse-modern-humans.html

Original paper, paywall access: http://www.pnas.org/content/early/2014/04/16/1405138111

earthstory:

HABOOB A haboob (Arabic: هَبوب “strong wind”) is a wall of sand and/or dust which is carried on an atmospheric gravity current. Most form when a thunderstorm produces a downdraft of cold air. The downdraft is pushed forward by the front of the thunderstorm cell, and drags dust and debris along with it as it travels across the terrain. Strong surface winds hurl this sand and dust into the air; the leading edge of the cold and dusty air is called the thunderstorm gust front. Haboob winds can travel 35-100 km/hr. Haboobs occur worldwide, including within the Sahara desert, across the Arabian Peninsula, through Kuwait and in the most arid areas of Iraq. They have been known to occur in Central Australia, associated with cold fronts. One of the more well-known haboobs of recent years is the haboob that hit Phoenix, Arizona, USA on July 5, 2011. The storm was up to 1,500m tall when it hit Phoenix and had a 161km wall on the leading edge. The dust storm moved at speeds up to 80 km/hr, and travelled 241-322km from Tucson to Phoenix. Haboobs normally form during the summer months in Phoenix, and can last up to 3 hours. Tucson, Arizona was also the site of the Dust Bowl on July 16, 1971, a devastating sandstorm.  China has also had its share of destructive haboobs – the most destructive hit many parts of far western China’s Xinjiang region 21 March 2012, with wind speeds in the popular tourist towns of Hami and Turpan reaching 183 kilometres per hour (photo is of a haboob in China). Simple diagram of haboob formation: http://apollo.lsc.vsc.edu/classes/met130/notes/chapter9/graphics/haboob.free.gif; http://bit.ly/Pt3XGA More complex diagram of haboob formation: http://bit.ly/TJ6JKJ -TEL Photos from large Iraqi haboob 2005: http://www.sunbelt-software.com/stu/iraq/sandstorm.htm View a timelapse of a haboob from Phoenix (USA) metro area on July 5th, 2011: http://www.scottwoodphotography.com/Weather/2011StormChasing/15913598_4nzjFs#!i=1370278891&k=RDCLM67&lb=1&s=Ahttp://www.ouramazingplanet.com/1524-haboob-dust-storm-hits-phoenix-arizona.html; http://phoenix.about.com/od/arizonamonsoon/qt/haboob.htm; http://www.newscientist.com/blogs/shortsharpscience/2011/07/howling-haboob-smothers-phoeni.html; http://www.bbc.co.uk/news/world-asia-china-17461442 Photo: China Foto Press

earthstory:

HABOOB

A haboob (Arabic: هَبوب “strong wind”) is a wall of sand and/or dust which is carried on an atmospheric gravity current. Most form when a thunderstorm produces a downdraft of cold air. The downdraft is pushed forward by the front of the thunderstorm cell, and drags dust and debris along with it as it travels across the terrain. Strong surface winds hurl this sand and dust into the air; the leading edge of the cold and dusty air is called the thunderstorm gust front. Haboob winds can travel 35-100 km/hr.

Haboobs occur worldwide, including within the Sahara desert, across the Arabian Peninsula, through Kuwait and in the most arid areas of Iraq. They have been known to occur in Central Australia, associated with cold fronts.

One of the more well-known haboobs of recent years is the haboob that hit Phoenix, Arizona, USA on July 5, 2011. The storm was up to 1,500m tall when it hit Phoenix and had a 161km wall on the leading edge. The dust storm moved at speeds up to 80 km/hr, and travelled 241-322km from Tucson to Phoenix. Haboobs normally form during the summer months in Phoenix, and can last up to 3 hours. Tucson, Arizona was also the site of the Dust Bowl on July 16, 1971, a devastating sandstorm.

China has also had its share of destructive haboobs – the most destructive hit many parts of far western China’s Xinjiang region 21 March 2012, with wind speeds in the popular tourist towns of Hami and Turpan reaching 183 kilometres per hour (photo is of a haboob in China).

Simple diagram of haboob formation: http://apollo.lsc.vsc.edu/classes/met130/notes/chapter9/graphics/haboob.free.gif; http://bit.ly/Pt3XGA
More complex diagram of haboob formation: http://bit.ly/TJ6JKJ

-TEL

Photos from large Iraqi haboob 2005: http://www.sunbelt-software.com/stu/iraq/sandstorm.htm
View a timelapse of a haboob from Phoenix (USA) metro area on July 5th, 2011: http://www.scottwoodphotography.com/Weather/2011StormChasing/15913598_4nzjFs#!i=1370278891&k=RDCLM67&lb=1&s=A

http://www.ouramazingplanet.com/1524-haboob-dust-storm-hits-phoenix-arizona.html; http://phoenix.about.com/od/arizonamonsoon/qt/haboob.htm; http://www.newscientist.com/blogs/shortsharpscience/2011/07/howling-haboob-smothers-phoeni.html; http://www.bbc.co.uk/news/world-asia-china-17461442

Photo: China Foto Press

earthstory:

The Bortle Scale and Light PollutionThe Bortle Scale is used by astronomers to rate the darkness of our skies. It ranges from 1 (darkest) to 9 (brightest). For most of us, our daily lives are spent beneath a radiance level of between 5 and 8 and rarely venture into areas ranked 3 or darker- and what a shame that is.Light pollution, while a testament to our technological advances, has blanketed our view of the universe and decoupled our relationship with the cosmos. For the millions of people living in areas where less than 20 stars can be seen in the night sky, it is practically impossible to imagine a natural sky blanketed with upwards of 2,500 stars backed by great ribbons of billions of stars which can be found in our Galaxy: The Milky Way.What are the effects of light pollution?From a research perspective, studies have demonstrated that our overuse of artificial light at night can increasingly be linked to sleep disorders, diabetes and cancer. Ecologically, habitats are disturbed and species are forced to adapt to or flee from this unnatural phenomenon. Environmentally, it is a huge waste of energy. Socially, increased light pollution can lead to a decrease in safety and security.From a psychological perspective, the lack of a brilliant dark sky can affect our humility. Without the nightly reminder of a vast cosmos, it is easy to forget how small we are, how insignificant. It is simple to imagine that we are the centre of all things when confined to a solitary closed ecosystem, this tasks gets harder when faced with the immensity of the universe before us.Before we invented civilisation, our ancestors embraced the darkness of space, wondered at the stars and contemplated the universe. Today, we immerse ourselves in artificial light; a lot of which is unnecessary and the result of bad habits. If we shield, downgrade or time our existing lighting infrastructure we could open the wonders of the night sky back up again.While artificial light has undoubtedly enriched our lives, the same has always been true of darkness- we do not need to be afraid of it.In the words of Sarah Williams “I have loved the stars too fondly to be fearful of the night.”-Jean

earthstory:

The Bortle Scale and Light Pollution

The Bortle Scale is used by astronomers to rate the darkness of our skies. It ranges from 1 (darkest) to 9 (brightest). For most of us, our daily lives are spent beneath a radiance level of between 5 and 8 and rarely venture into areas ranked 3 or darker- and what a shame that is.

Light pollution, while a testament to our technological advances, has blanketed our view of the universe and decoupled our relationship with the cosmos. For the millions of people living in areas where less than 20 stars can be seen in the night sky, it is practically impossible to imagine a natural sky blanketed with upwards of 2,500 stars backed by great ribbons of billions of stars which can be found in our Galaxy: The Milky Way.

What are the effects of light pollution?

From a research perspective, studies have demonstrated that our overuse of artificial light at night can increasingly be linked to sleep disorders, diabetes and cancer. Ecologically, habitats are disturbed and species are forced to adapt to or flee from this unnatural phenomenon. Environmentally, it is a huge waste of energy. Socially, increased light pollution can lead to a decrease in safety and security.

From a psychological perspective, the lack of a brilliant dark sky can affect our humility. Without the nightly reminder of a vast cosmos, it is easy to forget how small we are, how insignificant. It is simple to imagine that we are the centre of all things when confined to a solitary closed ecosystem, this tasks gets harder when faced with the immensity of the universe before us.

Before we invented civilisation, our ancestors embraced the darkness of space, wondered at the stars and contemplated the universe. Today, we immerse ourselves in artificial light; a lot of which is unnecessary and the result of bad habits. If we shield, downgrade or time our existing lighting infrastructure we could open the wonders of the night sky back up again.

While artificial light has undoubtedly enriched our lives, the same has always been true of darkness- we do not need to be afraid of it.

In the words of Sarah Williams “I have loved the stars too fondly to be fearful of the night.”

-Jean

terra-mater:

Copenhagen

The theme for Earth Day 2014 is ‘green cities’. As more and more people move to cities in search of jobs – and the reality of climate change becomes increasingly clear – the need to create sustainable communities is more important than ever. Recognised this year as the European Green Capital, Copenhagen has set a prime example with investments in sustainable technology, forward-thinking public policy and an educated and active public. The Danish city is a good model in terms of urban planning and design, and is working towards becoming carbon-neutral by the year 2025.

Image credit & copyright: Airbus Defence and Space

terra-mater:

Copenhagen

The theme for Earth Day 2014 is ‘green cities’. As more and more people move to cities in search of jobs – and the reality of climate change becomes increasingly clear – the need to create sustainable communities is more important than ever. Recognised this year as the European Green Capital, Copenhagen has set a prime example with investments in sustainable technology, forward-thinking public policy and an educated and active public. The Danish city is a good model in terms of urban planning and design, and is working towards becoming carbon-neutral by the year 2025.

Image credit & copyright: Airbus Defence and Space

earthstory:

Earth Day: The Urban Heat Island Effect-When summer temperatures rise to uncomfortable levels, you can be guaranteed that being within the limits of a large city does not help anything. In fact, it will be even warmer. This phenomenon of increased temperatures in urban areas is termed the ‘Urban Heat Island Effect’ and it result from urban infrastructure and design.The ‘concrete jungles’ of our planet are crammed with barren walls, roofs and streets; many of which are dark in colour. By day, concrete and asphalt structures absorb the ultraviolet radiation from the sun and then by night, this radiation is released as thermal infrared radiation which creates a dome of higher temperatures over cities.Contrastingly, natural landscapes host vegetation and canopies of biomass to create cooler air temperatures due to latent heat; when water changes from a liquid to a gas, energy is needed to overcome the molecular force of attraction between the particles. So, through the process of evaporative cooling, excess heat is utilised by the natural environment.The influence of the Urban Heat Island effect is profound. In a city with 1 million people or more, the annual mean air temperature can be more than 1–3°C (1.8–5.4°F) warmer than its surroundings. In the evening, the difference can be as high as 12°C (22°F) (USEPA)JeanFor more information, see here: http://www.epa.gov/heatisland/Image courtesy of http://c3headlines.typepad.com/.a/6a010536b58035970c017744ad1afa970d-pi

earthstory:

Earth Day: The Urban Heat Island Effect-

When summer temperatures rise to uncomfortable levels, you can be guaranteed that being within the limits of a large city does not help anything. In fact, it will be even warmer. This phenomenon of increased temperatures in urban areas is termed the ‘Urban Heat Island Effect’ and it result from urban infrastructure and design.

The ‘concrete jungles’ of our planet are crammed with barren walls, roofs and streets; many of which are dark in colour. By day, concrete and asphalt structures absorb the ultraviolet radiation from the sun and then by night, this radiation is released as thermal infrared radiation which creates a dome of higher temperatures over cities.

Contrastingly, natural landscapes host vegetation and canopies of biomass to create cooler air temperatures due to latent heat; when water changes from a liquid to a gas, energy is needed to overcome the molecular force of attraction between the particles. So, through the process of evaporative cooling, excess heat is utilised by the natural environment.

The influence of the Urban Heat Island effect is profound. In a city with 1 million people or more, the annual mean air temperature can be more than 1–3°C (1.8–5.4°F) warmer than its surroundings. In the evening, the difference can be as high as 12°C (22°F) (USEPA)

Jean

For more information, see here: http://www.epa.gov/heatisland/

Image courtesy of http://c3headlines.typepad.com/.a/6a010536b58035970c017744ad1afa970d-pi

earthstory:

VON KÁRMÁN VORTEX STREET, SELKIRK ISLAND, OFF SOUTH AMERICA The pattern shown in these swirling clouds is known as a von Kármán vortex street, named after Theodore von Kármán. They occur when a more viscous fluid flows through water and encounters a cylindrical object, creating vortices in the flow. These structures were first noticed in the laboratory by fluid dynamicists. Study of these vortices are very important in the understanding of laminar and turbulent fluid flow; these control a wide variety of real-world phenomena, like the lift under an aircraft wing and Earth’s weather. In the photo, the Alejandro Selkirk Island, off the Chilean coast, is acting like the cylinder. A vortex street is shown disrupting a layer of stratocumulus clouds which are low enough to be affected by the island, which is nearly 1.6 km above sea level and 1.5 km in diameter. When the wind-driven clouds run into the obstacle of the island, they flow around it clockwise and anticlockwise to form the beautiful spinning eddies, advecting hundreds of kilometres downwind to make a street 10,000 times longer than those made in the laboratory. A vortex street can be observed only over a given range of Reynolds numbers (Re), normally above a limiting Re value of about 90. The Reynolds number is a measure of the ratio of inertial to viscous forces in the flow of a fluid and may be defined as: Re = Vd/v where: d = the diameter of the cylinder around which the fluid is flowing. V = the steady velocity of the flow upstream of the cylinder. v = the kinematic viscosity of the fluid. You can view a simple animation of the von Kármán vortex street here: http://upload.wikimedia.org/wikipedia/commons/b/b4/Vortex-street-animation.gif A more complex animation is here (Reynolds number Re = 250): http://www.youtube.com/watch?v=IDeGDFZSYo8 -TEL The image was taken by the Landsat 7 satellite in September 1999. Credit: Bob Cahalan/NASA, USGShttp://www.wired.com/wiredscience/2010/05/gallery-clouds/; http://weathervortex.com/wakes.htm

earthstory:

VON KÁRMÁN VORTEX STREET, SELKIRK ISLAND, OFF SOUTH AMERICA

The pattern shown in these swirling clouds is known as a von Kármán vortex street, named after Theodore von Kármán. They occur when a more viscous fluid flows through water and encounters a cylindrical object, creating vortices in the flow. These structures were first noticed in the laboratory by fluid dynamicists. Study of these vortices are very important in the understanding of laminar and turbulent fluid flow; these control a wide variety of real-world phenomena, like the lift under an aircraft wing and Earth’s weather.

In the photo, the Alejandro Selkirk Island, off the Chilean coast, is acting like the cylinder. A vortex street is shown disrupting a layer of stratocumulus clouds which are low enough to be affected by the island, which is nearly 1.6 km above sea level and 1.5 km in diameter. When the wind-driven clouds run into the obstacle of the island, they flow around it clockwise and anticlockwise to form the beautiful spinning eddies, advecting hundreds of kilometres downwind to make a street 10,000 times longer than those made in the laboratory.

A vortex street can be observed only over a given range of Reynolds numbers (Re), normally above a limiting Re value of about 90. The Reynolds number is a measure of the ratio of inertial to viscous forces in the flow of a fluid and may be defined as:
Re = Vd/v
where:
d = the diameter of the cylinder around which the fluid is flowing.
V = the steady velocity of the flow upstream of the cylinder.
v = the kinematic viscosity of the fluid.

You can view a simple animation of the von Kármán vortex street here: http://upload.wikimedia.org/wikipedia/commons/b/b4/Vortex-street-animation.gif

A more complex animation is here (Reynolds number Re = 250): http://www.youtube.com/watch?v=IDeGDFZSYo8

-TEL

The image was taken by the Landsat 7 satellite in September 1999. Credit: Bob Cahalan/NASA, USGS
http://www.wired.com/wiredscience/2010/05/gallery-clouds/; http://weathervortex.com/wakes.htm

earthstory:

Scattered by conesVolcanic cones (150 in total) on Marion Island almost appear are spots on a teenagers face. In addition a large portion of the island is covered in A’a and pahoehoe flows, the vegetated ones could be less than 100 years old. Marion is one of the peaks of a large submarine shield volcano that rises 500m from the bottom of the sea. Mascarin peak, the highest point on Marion is 1242m high. Eruptions have occurred in 1980 and 2004. It’s South Africa’s only historically known active volcano.Together with smaller neighbor Prince Edward Island Marion is collectively known as the Prince Edward islands and is located 1769 km from the South African mainland and a little bit further away from Antarctica.On average it rains 320 days a year. Thus Marion is rightly known as one of the cloudiest places in the world. Due to the wetness of the climate the island is covered with bog, lichen and other subarctic vegetation. There is not much difference between winter and summer on the island, it is always wet, with threat of snow and frost. The strong westerly winds that roam the island are branded the Roaring FortiesMarion was discovered by the Dutch ship Maerseveen in 1663, however it was not until 1772 that someone actually sat foot on it. Frenchman Joseph Marion du Fresne was in the preconception that he had made it to Antarctica. It took him 5 days to discover he was on two small islands. Again in 1803 the island was visited by sealers. In 1947 South Africa annexed the island and based a meteorological station there. There are no permanent inhabitants.The introduction of cats on the island (in the first place brought here to deal with the problem of mice) caused the grey petrel to become extinct. Supposedly the cats managed to eat about half a million birds in 1975 alone. The cat eradication programme finally managed to get rid of the cats in 1991.-OW-Image: NASA Erath Observatory.References:http://www.sanap.ac.za/sanap_marion/sanap_marion.htmlhttp://www.volcano.si.edu/volcano.cfm?vn=234070

earthstory:

Scattered by cones

Volcanic cones (150 in total) on Marion Island almost appear are spots on a teenagers face. In addition a large portion of the island is covered in A’a and pahoehoe flows, the vegetated ones could be less than 100 years old. Marion is one of the peaks of a large submarine shield volcano that rises 500m from the bottom of the sea. Mascarin peak, the highest point on Marion is 1242m high. Eruptions have occurred in 1980 and 2004. It’s South Africa’s only historically known active volcano.

Together with smaller neighbor Prince Edward Island Marion is collectively known as the Prince Edward islands and is located 1769 km from the South African mainland and a little bit further away from Antarctica.
On average it rains 320 days a year. Thus Marion is rightly known as one of the cloudiest places in the world. Due to the wetness of the climate the island is covered with bog, lichen and other subarctic vegetation. There is not much difference between winter and summer on the island, it is always wet, with threat of snow and frost. The strong westerly winds that roam the island are branded the Roaring Forties

Marion was discovered by the Dutch ship Maerseveen in 1663, however it was not until 1772 that someone actually sat foot on it. Frenchman Joseph Marion du Fresne was in the preconception that he had made it to Antarctica. It took him 5 days to discover he was on two small islands. Again in 1803 the island was visited by sealers. In 1947 South Africa annexed the island and based a meteorological station there. There are no permanent inhabitants.

The introduction of cats on the island (in the first place brought here to deal with the problem of mice) caused the grey petrel to become extinct. Supposedly the cats managed to eat about half a million birds in 1975 alone. The cat eradication programme finally managed to get rid of the cats in 1991.

-OW-

Image: NASA Erath Observatory.

References:
http://www.sanap.ac.za/sanap_marion/sanap_marion.html
http://www.volcano.si.edu/volcano.cfm?vn=234070