Saturday, October 31, 2015

Paris, the city of... underground mushrooms

The famous underground catacombs of Paris attract thousands of tourists each year, although only 200 can go in at a time.

However, the catacombs also provide an environment which lends itself to raising Champignons de Paris aka button/Portobello mushrooms.

Champignons de Paris: the famous mushroom and their city farmers - France Today
http://www.francetoday.com/articles/2015/03/16/champignons_de_paris.html

Video: French chefs champion the return of traditional mushroom farming - AP

https://www.youtube.com/watch?v=AGEqzac0saM


Angel Moioli of Champignonnière Les Carrières growing mushrooms

Kīpuka

What's a Kīpuka?

In volcanic areas like Hawaii, a Kīpuka is an area of land that gets surrounded by lava, forming an "island" or hole in the lava that remains intact. It provides an island of life, surrounded by sheer black rock, where many species often thrive. Often, the Kīpuka area is a raised bump or has some other topographic irregularity that kept lava from covering it. Kīpukas can be just a few feet or can be several square miles.


Kīpukas also provide a source organic material which can be used to recolonize the lava-covered areas around it. Seeds and spores from the Kīpuka can blow or wash over onto lava, restarting life there through primary succession.


Ongoing eruptions from Kīlauea volcano, shown in the example below, cover 90% of the volcano's surface every 100 years. The plant community has adapted to bounce back very fast through primary succession.



Kīpuka on Kīlauea volcano on the island of Hawaiʻi in Hawaii


Craig Childs showing primary succession by ferns on lava next to a kīpuka
http://www.lastwordonnothing.com/2014/11/12/what-destruction-has-wrought/


USGS - see lower section on kīpukas

http://hvo.wr.usgs.gov/volcanowatch/archive/1999/99_01_21.html

Craig Childs on Kipukas
http://www.lastwordonnothing.com/2014/11/12/what-destruction-has-wrought/

Kipukas - NPS
http://www.nps.gov/crmo/learn/nature/kipukas.htm

Friday, October 30, 2015

China's migrant children

China's migrant children - The Guardian
https://www.youtube.com/watch?v=_clX1WACZ6Y

A poignant look at the children of Chinese rural migrants to Beijing. China's hukou household registration system, often said to be China's caste system, requires people to register as rural or urban dwellers, but many rural people migrate to cities. Problem is, they and their children do not get benefits from government when they are away from their registered home.

Tuesday, October 27, 2015

Where do legal immigrants come from in your state?

Blatt_Immigrant_1

Biggest immigrant groups by state - Slate
http://www.slate.com/articles/arts/culturebox/2014/05/immigration_map_what_are_the_biggest_immigrant_groups_in_your_state.html

Cubans in Kentucky?
Filipinos in West Virginia?
Bhutanese in North Dakota?
Somalis in Maine?
Burmese in Indiana?

Threw me for a loop. Who knew?


Farm workers: despite youth employment, still a shortage

Thought working age was 16? Not for farming jobs. In many states in the US, you can be as young as 12 years old and work on a farm.

US Department of Labor - State Child Labor Laws Applicable to Agricultural Employment
http://www.dol.gov/whd/state/agriemp2.htm

In addition, most of the 1 million farm workers in the US are immigrants and up to half of them are illegal.

US farmers depend on illegal immigrants
http://www.voanews.com/content/us-farmers-depend-on-illegal-immigrants-100541644/162082.html
But even with youth and illegal immigration, there is still a major farm labor shortage.

The shortage of farm workers and your grocery bill - CNBC
http://www.cnbc.com/2014/05/15/migration-reform-stops-farm-labor-shortage.html

Wednesday, October 21, 2015

99 homes

99 Homes is a movie that came out recently about the foreclosure crisis. If it is playing near you it is worth seeing. It does a good job of showing some of the realities and consequences of predatory loans and foreclosures. The US was not the only place to have a foreclosure crisis, European countries had a crisis as well with Latvia of all places having the only rate higher than the US for 2009.

Foreclosures occur when a homebuyer cannot make the payments and the bank takes the house back. The homebuyer is often stuck having to pay off the difference between the price they originally paid and the current value.

There have been two waves of the foreclosure crisis:
Wave 1 was largely predatory loans given to immigrants and minorities. This peaked in the late 2000s.
Wave 2 (still going on) is largely wealthier buyers who bought far more expensive homes than they could really afford

The county I teach in Prince William County, VA was Virginia's leader in foreclosures with 16% of the county's homes being foreclosed on in the last 10 years.

Check out these videos:

Get ready for another round of the foreclosure crisis
http://www.pbs.org/newshour/bb/get-ready-another-round-foreclosure-crisis/

Subprime loans
https://www.youtube.com/watch?v=VXcfbxSnzP0


Monday, October 19, 2015

Who's next for the EU?

What country will join the European Union next? Croatia was the last country to join, in 2013, and the odds are another Balkan country will be next, very ironic given the wars and genocide that went on there just 20 years ago.



Debating Europe: Which country should join the European Union next?
http://www.debatingeurope.eu/2014/03/20/which-country-should-join-the-european-union-next/#.ViVyCn6rQdU

Sunday, October 18, 2015

Dynamic Russia

Russia is a much more complex and diverse country than many people realize, with dozens of individual ethnic groups including Muslims and even Buddhists with their own autonomous republics. Google names like the Chukchi, Nenets, Yakut, and Tatar peoples to see how and where some of the ethnic groups live.
Kul Sharif Mosque in Kazan, Tatarstan, Russia

Economic issues - "
almost like 83 countries all put together."
Russia's economy is now is in the midst of tight sanctions that the US and EU are now squeezing and we may be seeing a domestic meltdown there in the not so near future. Putin's antics abroad are in part a diversion from the economic difficulties they have at home, but they can't run on diversions forever.

Russia runs largely on natural resources and needs to develop more higher-level manufacturing and services industries. The high rate of government corruption, however, makes this development slow in coming. Russia suffers from "brain drain," smart, educated people who leave to pursue research and opportunities in other countries.
Russia has a great deal of disunity, as the video below mentions it is "83 regions, almost like 83 countries all put together," with lots of regional dissent, very difficult to manage.

Video: Russia's perfect economic storm
https://www.youtube.com/watch?v=_mzcCVKgMi0

Population issues
The large population decline in Russia over the last century was in part due to the deaths during the famines and murders of the Communist era and then later in the 1960s and 1970s the fertility rate became very low as Russia became the world leader in abortions. For many of those years Russia averaged three abortions per woman in a lifetime--hard to believe but true. The communist government encouraged abortion as a means of birth control. Even today after abortion rates have declined sharply, if you can believe it, Russia has more abortions than live babies born and still leads the world in abortions.

On the map below, Russia's Siberian regions are growing while the core, which includes Moscow and St. Petersburg, are shrinking fast.





Siberia
Siberia is extremely cold in winters. Russia is the only country in the world that has created many major settlements of 1 million plus in regions that are subzero for large portions of the year. Cities like Novosibirsk and Krasnoyarsk average close to zero 3 months out of the year, and the coldest of all, Yakutsk, the coldest major city in the world, has a January average temperature of -43F.

Here's a short clip of life in Yakustk on a day at -46--I like the fish market, no refrigeration necessary


Life in Yakustk on a day at -46
https://www.youtube.com/watch?v=qVHofQB1xCw

There is talk that with global warming Siberia could become slightly easier to access, but it remains to be seen how much of a change it will bring.

Three Siberian rivers, all huge
Russia's three great Siberian rivers (see chapter maps) the Ob, Yenisey, and Lena are some of the longest rivers in the world that most people have never heard. This remote and cold, deep in Siberia, running north into the Arctic Ocean, which could be open for longer periods for shipping with global warming, see the earlier Announcement and map posted.

Take a look at this photo series

Life on the Yenisey River
http://photo.sf.co.ua/id246


Russia's Far East: great long term potential
Russia's Far East 
simply has a huge amount of empty space plus a great coastal location on the Pacific Rim near China, Japan, and Korea. It has huge potential for settlements and industries, which the central government has never developed, in part because it is distance from Moscow. It is actually farther from Moscow to Vladivostok, Russia than it is from Washington, DC to Moscow.

Here are some economists who are excited about the potential for Russia's Far East:

Tapping the potential for Russia's Far East
https://www.youtube.com/watch?v=d7EZy75BVvg


photo
Logging on the Yenisey River in Siberia






Want to go to college - a good college - in English for free? Head to the Nordic countries

Want to got to college - a good college -in English for free? Head to the Nordic countries.

100% free tuition all programs:
-Norway
-Iceland
-Finland

Free PhD programs only:
-Sweden

Nordic countries are world leaders in pharmaceutical research and many other science fields. As a region, they have the highest standards of living in the world.

7 countries where Americans can study at universities, in English, for free (or almost free)
https://www.washingtonpost.com/news/worldviews/wp/2014/10/29/7-countries-where-americans-can-study-at-universities-in-english-for-free-or-almost-free/

"Since 1985, U.S. college costs have surged by about 500 percent, and tuition fees keep rising. In Germany, they've done the opposite."

Why study at a Scandinavian university?
http://www.topuniversities.com/student-info/choosing-university/why-study-scandinavian-university

Friday, October 16, 2015

Elizabeth Warren on foreclosures

Elizabeth Warren on foreclosures - Dan Rather Reports
https://www.youtube.com/watch?v=Hk_nzAj_cZs

"Income has flattened out... but core expenses have all gone up, and that's left the basic family with less money than a generation ago.

We have not a few people, we have literally tens of millions of Americans, hard-working, play by the rules,  middle class people, people who got decent educations, people who got jobs, people who go married, moved out, bought houses, the backbone of who we are as America, those people are now hanging on by their fingernails."

Thursday, October 15, 2015

Nice country, few jobs for refugees in Sweden

Sweden is often seen as a place where everything works right, everybody has a great standard of living. But for refugees, while they are safe and secure, getting a job has been very difficult.

"Only 53 percent of refugees who arrived in 2003 had found jobs by 2013. Of those who arrived two years ago, only about 30 percent are now employed.  Sweden’s unemployment rate is currently 7 percent."

Welcome to Sweden, you'll get a job in a decade

http://www.bloomberg.com/news/articles/2015-09-30/refugees-welcome-to-sweden-you-ll-get-a-job-in-a-decade

Syrian exodus nutshell

The ideas of push and pull factors are central to Migration Geography. Push factors are the reasons people leave a place, pull factors are the reasons people are attracted to a new place. There can be lots of each.

There are also intervening obstacles, everything from language learning to oceans to deserts to walls.

Syria is in the midst of a civil war that involves no less than five groups fighting each other, each with their own chunk of territory shown in the map below:

-The ruling Assad regime which the US would like to see gone
-Free Syrian Army (rebels)
-ISIS
-Al Nusra/Al Quaeda
-The Kurds - ancient ethnic group


In short, Syria is a total mess, like a streetfight between five gangs. Few people there find reasons to stay.


syriaarmies

-Syria's total population is around 23 million
-Total number of Syrian refugees abroad today is over 4 million and rising
-So, pretty soon 1/5 of Syrian citizens will no longer live in Syria

-Add 6.5 million internally displaced within Syria, and half the country will be displaced either internally or externally

This weeks videos in Topic 2 show many intervening obstacles and the pull factors that are drawing migrants to Europe.  

Map: Syrian asylum claims in Europe and registered refugees in the Middle East


Aid and Asylum Map
http://syrianrefugees.eu/?page_id=199

Migrant crisis: Merkel says EU must secure external borders

http://www.bbc.com/news/world-europe-34535933

Welcome to Sweden, you'll get a job in a decade
http://www.bloomberg.com/news/articles/2015-09-30/refugees-welcome-to-sweden-you-ll-get-a-job-in-a-decade

Wednesday, October 14, 2015

Eurosceptics vs. Europhiles... and the middle ground

Take a look at these two videos where the sparks fly on the floor of the European Parliament over Greece staying or leaving (a "Grexit") the EU. It also illustrates two visions of the EU, though I doubt either one speaks for the average EU citizen.

The two speakers are

-Nigel Farage, who ironically represents the UK in the EU Parliament and yet uses his seat to blast the EU's very existence. He wants to facilitate Greece's exit in this video, but also wants to facilitate the UK's exit in 2017 (a "Brexit")

Eurosceptic Nigel Farage (UK) on Grexit
https://www.youtube.com/watch?v=ai43B588_co

-Guy Verhofstadt who represents the Netherlands and believes in a unified "United States of Europe" and wants to keep Greece in the EU


Europhile Guy Verhofstadt (Belgium) on Grexit
https://www.youtube.com/watch?v=P84tN0z4jqM
|
Does one seem more convincing to you?
Nigel Farage is after all the "oral assassin" and Guy definitely has that Belgian accent. From Farage's side, like other conservatives, the EU is a "project" of elites that does not respect not only the differences among countries of Europe but also the fact that they have elected representative governments, as some major aspects of the EU like the EU Comissioners (different from the Parliament he sits in) are not elected. Having said that, other EU aspects are elected, like the seat in Parliament that he occupies. The EU system of institutions is a little more complex than the US, they have a few more bodies and sometimes they seem to do redundant functions, another major issue.

From Guy's side, many like him believe that European countries won't have real clout on the world stage unless they band together, they won't be able to compete with the big boys like the US, China, and Russia if Europe is a smorgasbord of smaller countries each going their own way. Having said that, the UK would still be in a good spot alone as it has a strong economy, is still fairly large, and typically has its own sort of union with the US on just about all foreign policy matters, something called the "special relationship" in international relations. 
https://en.wikipedia.org/wiki/Special_Relationship

Belgium, however, would not really be a big player on the world stage without the EU. So Guy believes a United States of Europe is necessary, he actually said that in another video. Farage believes that it is wrong to try to replace the original set of states that are elected with a new Eurostate, sometimes termed a "universalist" project, that is not really elected. Either way, there is either unity or chaos, but the question is whether the unity is at the larger scale or more national scale.

"Eurosceptic" is the term usually used for those who are anti-EU. Eurosceptics won big in the 2014 elections around Europe. They often ran on anti-immigrant platforms. The current refugee crisis is actually fanning those flames as some Europeans are looking at the thousands pouring in, needing jobs in countries that already have high unemployment.

Others, though, would argue that fertility rates and population numbers have been low in countries like Germany so they could use more people. Then there is the issue of many Europeans fearing that Islamic immigrants will dilute their culture.

The middle ground
As in so many "left vs. right" debates in the US, often neither side speaks for the majority opinion.
http://nationalinterest.org/commentary/how-europhiles-eurosceptics-oversimplify-the-eu-9324
This article mentions how both sides draw caricatures:

-Europhiles have lumped being simply nationalists and pro-smaller scale government with being anti-semitic and ethnically-intolerant. Meanwhile, Europhiles paint themselves as crusaders against intolerance, even though "
 there is very little the EU does concretely to fight bigotry, besides passing nicely-worded resolutions."

Creative parking in Europe

Europe's population density issues have led to a lack of parking, and in many areas people have taken to news ways of parking: on sidewalks, perpendicular with Smart Cars.

One result when cars park on sidewalks is that pedestrians are forced onto the street, causing more accidents.

Another issue is narrow streets.


Ipswich, England

Smart car parked facing into the road
Smart car in England--she got a ticket but beat it in court:
"A parking penalty tribunal adjudicator ruled that Mrs. Price had not breached any traffic regulation by leaving her car as she did in Stroud."
http://www.express.co.uk/news/uk/547313/Smart-car-owner-Vanessa-Price-was-fined-parking-the-wrong-war
“Mrs Price, of Stroud, Gloucestershire, said: 'If you go to the Smart website, they show you pictures of their cars parked in this way.'”



Moscow


Brussels


Europe: the land of tight streets, scooters and Smart cars

Diplomas and stuffed animals


Well-educated young Spaniards move back in with their parents - Der Spiegel
http://www.spiegel.de/international/europe/well-educated-young-spaniards-move-back-in-with-parents-a-881525.html

"According to figures by the European Union statistics agency Eurostat, 37.8 percent of Spaniards under 35 are now living with their parents."

"Fariñas, a petite woman with a long girlish haircut, completed her state examination in education in 2006, and then earned additional credits to qualify for adult education. She also obtained two masters' degrees. Still, she hasn't managed to move out of her apple-green children's room, complete with stuffed animals on the pullout sofa."

Good videos explaining EU refugee migration crisis

Good videos explaining EU refugee migration crisis

These videos give an overview of some of the major issues, so many facets to this situation. It connects the wars against Islamic extremism to the politics of the European Union.

-Where are the biggest refugee groups coming from?
-What is the Schengen Zone and why is it being challenged by the refugee crisis?
-Which countries are receiving extremely high numbers of migrants?
-Why are many migrants seeking to get to Germany?
-What are some of the challenges European countries are having in receiving migrants?
-What are some of the challenges migrants face after they reach Europe?

1. Overview
a) Migrant crisis explained - Yahoo
- 5 min
https://www.youtube.com/watch?v=Q8ROTJR6Z-s          

b) The European refugee crisis and Syria explained
https://www.youtube.com/watch?v=RvOnXh3NN9w

2. Schengen Zone
a) What is the Schengen Zone? 2:30
https://www.youtube.com/watch?v=uz4vlS1QGhw

b)  The role of the Shengen Zone in the migration crisis - 2 min
https://www.youtube.com/watch?v=sGegWCS24ZE

3. Why so many migrants are heading to Germany and Sweden? - 2 min
http://www.telegraph.co.uk/news/worldnews/europe/11856382/Why-are-migrants-heading-to-Germany-and-Sweden.html

4. Obstacles refugees face
a) We walk together: a Syrian family's journey to the heart of Europe
-15 min
https://www.youtube.com/watch?v=ubGhzVdnhQw

b) Refugee family smuggled from Syria to Greece
https://www.youtube.com/watch?v=QPnxc4vvKZk

5. EU's new plans to relocate refugees - Bloomberg - 1:10
http://www.bloomberg.com/news/articles/2015-09-13/germany-reinstates-austria-border-controls-amid-refugee-crisis

migrantmap

Infografik Flüchtlinge Balkanroute September mit Kroatien 2015 Englisch


Friday, October 9, 2015

New Caledonia: the nickel island

On a trip in Malaysia last winter break I met a Chinese-Canadian guy named Tom who is a mining engineer. He said he has worked in many countries including China, Malaysia, Saudi Arabia, and New Caledonia. He said "New Caledonia doesn't have nickel, it is nickel." Sure enough, New Caledonia contains 10% of the world's nickel supply.

new+caledonia+map

New Caledonia nickel under threat - Al Jazeera
https://www.youtube.com/watch?v=HJXP3d_yDVI

Good explanation of coral reef formation

Good explanation of coral reef formation
https://www.youtube.com/watch?v=btRCAQHqbdY

Barrier reef + sand deposition over time = atoll

Belize's Glover's Reef lies along the Mesoamerican Barrier Reef, the largest such system in the Western hemisphere. Photo © R.T. Graham
Glover's Reef, Belize

Dialect continuum

A dialect continuum is like the game of telephone. A language dialect at one end of its geographic range slowly changes across space so that by the time it reaches the other end it is unintelligible to the original form, despite being part of the same dialect.

Dialect contiunuum - Wikipedia
https://en.wikipedia.org/wiki/Dialect_continuum


World countries by ethnic diversity

A revealing map of the world's most and least ethnically diverse countries
https://www.washingtonpost.com/news/worldviews/wp/2013/05/16/a-revealing-map-of-the-worlds-most-and-least-ethnically-diverse-countries/

Most diverse: Uganda
Most homogenous: Japan and the Koreas

-It is interesting that the US "melting pot" only has average ethnic diversity
-Several of the most homogenous are geographically isolated ex. Nordic, NW Europe, Australia, Japan and Koreas


Tuesday, October 6, 2015

China's Uyghur region contains more than Uyghurs and Chinese


Xinjiang in the remote far west is one of five autonomous ethnic regions in China, like Tibet and Inner Mongolia. At pop. 22 million, it would be the 3rd most populous US state after California and Texas and larger than Florida, yet ranks in the bottom third of China's provinces in population. It would be the 2nd largest US state by area at 642,800 square miles, just a hair shy of Alaska and well over twice the size of Texas.

Xinjiang multiethnic and today very controversial. It is often called the Uyghur region of China because it is the homeland of the Uyghurs, an Islamic Turkic people similar to the neighboring Kazakhs, Uzbeks, Kyrgz, Tajiks, etc. who are all traditionally nomads of the vast, flat Central Asian steppe.

So historically and ethnically, Xinjiang is like an "honorary stan," similar to the four Turkic stans which it borders to the west but currently part of China, controlled from the east. The strong independence movement in Xinjiang, wanting to break from China, calls the future state they seek "East Turkestan" (see map below) as it is the easternmost of the Turkic regions.



There is a ton of news recently about China moving Han Chinese people into Xinjiang in droves, building cities and huge numbers of new homes for the Han, and declaring various aspects of traditional Islamic Uyghur culture illegal including head scarves, men's traditional beards, and a few months ago even fasting during the month of Ramadan.

China bans fasting during Ramadan
http://www.aljazeera.com/news/2015/06/china-bans-ramadan-fasting-muslim-region-150618070016245.html

On the ethnic map below, the bottom half of Xinjiang where 80% of Uyghurs live is centered in the Tarim Basin, at the center of which is the Takla Makan Desert. (Good maps of Xinjiang are hard to find!) This core Uyghur region the Tarim Basin is separated from the northern Xinjiang by the vast Tien Shan Mountains.


Ethnic groups in Xinjiang: Uyhghur, Han Chinese, Kazakh


The vast, flat steppe across Eurasia, traditionally home to nomadic cultures since ancient times

Multiethnic, majority Islamic
One thing I did not realize, however, was that there are two other large ethnic group in Xinjiang, both Islamic like the Uyghurs:

-the Kazakhs who number 1.5 million in Xinjiang and make up 6.5%, dominating the northernmost subregion.

-the Hui who are ethnically Chinese (not Turkic) but Islamic make up 4.5%

Currently the demographics stand:

46% Uyghurs
40% Han Chinese
6.5% Kazakh
4.5% Hui

So overall, Xinjiang is around 57% Islamic spread among 3 Islamic ethnic groups Uyghur, Kazakh, Hui. China is trying to change the majority by relocating Han Chinese to the region, but it will take a while before the majority changes.


Prince William County: Virginia's foreclosure capital

Prince William County (PWC) has the highest foreclosure rate in Virginia and by far the highest in the DC metro area. PWC has just over 133,000 homes and adding up years 2006-12 below there were over 17,000 foreclosures--which represents 13% of the housing stock in the county that was foreclosed on. Yikes.

Prince William Dept. of Finance Estimate of General County Revenue
http://www.pwcgov.org/government/dept/finance/documents/fy14-18%20proposed%20revenue%20book.pdf

From page 8 of the Prince William Dept. of Finance doc above:

"The following foreclosure statistics indicate the severity of the [foreclosure] crisis since 2006:

2006:........ 249 foreclosures
2007:.........2,805
2008:........ 6,412
2009:.........3,308
2010:.........2,083
2011:……....1,426
2012…….......959"


See

Why are Foreclosure Rates in Prince William County, the City of Manassas, and the City of Manassas Park High When Compared to Other Parts of the Washington, DC Metro Area?https://www.wm.edu/as/publicpolicy/documents/prs/prince-william.pdf


Washington Post - Prince William County real estate map
http://www.washingtonpost.com/wp-srv/realestate/features/2009/housing-review/property-values/prince_william.html

"Homes in some areas around Manassas lost half their value. In some places, though, falling prices triggered more sales."

Median Purchase Price

January through December
Zip Code'07 Total Homes Sold'07 Median Purchase Price'08 Total Homes Sold'08 Total Homes SoldChange in Median Price
20109291299,000177219,950-7,9050
20110405335,0001,007175,000-160,000
20111278364,950549180,000-184,950
20112404520,000232440,282-79,718
20136630445,653351385,000-60,653
201378392,5002272,500-120,000
201438871,5808968,00096,420
20155687436,690388391,065-45,625
20169514529,545335473,695-55,850
2018173525,00045440,000-85,000
22025349395,371194333,500-61,871
22026179318,00082267,500-50,500
2212519501,71512500,000-1,715
221342257,5001120,000-137,500
22172112489,49587402,095-87,400
221911,082371,039604320,650-50,389
22192850343,950393309,000-34,950
22193864349,000494296,782-52219
Total6,755390,0004,961300,000-90,000
SOURCE: Full-value transactions as reported by Prince William, Manassas and .Manassas Park
CHART/MAP: Dan Keating and Gene Thorp - The Washington Post

Sunday, October 4, 2015

Glass frogs

Good short video on glass frogs which have transparent bellies so that you can see their organs including the heart. They also have translucent skin.

Video - Glass frogs: crystals of the rainforest
https://www.youtube.com/watch?v=BVFMtELtSic

also

New species of glass frog found in Costa Rican mountains
http://www.ticotimes.net/2015/04/15/new-species-of-glass-frog-discovered-in-costa-rican-mountains



Centrolenidae range.PNG
Glass frog species range

Thursday, October 1, 2015

Varieties of twilight

Twilight occurs at dawn and dusk, the times when the sun itself is entirely below the horizon but sunlight glows over the horizon. People who live inside the Arctic Circle like in northern Alaska or Norway get their only daily light from twilight for several months out of the year, during the months of polar night (24 hours with no sun over the horizon).

Twilight comes in several strengths, each one named for the type of function that can be done by it. These strengths listed below are important to a variety of people like
-photographers
-pilots of ships and planes
-people in Arctic regions who get long periods of twilight, sometimes their only light of the day if they live inside the Arctic Circle where during polar night months the sun does not rise over the horizon

In order of dark, darker, darkest:

Civil twilight - brightest twilight, can distinguish terrestrial objects clearly (i.e. perform "civil" functions like driving, etc.) Only the brightest stars appear.
Sun angle is up to 6 degrees below horizon
Civil twilight in London

Nautical twilight
- sea horizon line is visible which allowed sailors to measure star heights from the horizon. Can distinguish most stars and objects' general shapes but not their details. Need artificial light to see objects clearly.
Sun angle is 6 to 12 degrees below horizon
Nautical twilight overlooking St. Peres de Ribes, Spain and the Mediterranean Sea

Astronomical twilight - can distinguish stars easily, twilight is barely perceptible, cannot distinguish sea horizon.
Sun angle is 18 degrees below horizonComet & Moon in Astronomical Twilight (astronomy sunrise+sunset ). Photo by CJSprinkle
Astronomical twilight, Simi California

When each period of twilight ends, there is a dusk as shown in the fishing diagram below.