台風一過の7月11日。東京都内では内側に赤みを帯びて光る不思議な虹が目撃された。Twitterにその様子を撮影した写真が投稿され、1日で1万件以上リツイートされている。
虹は、空中の水滴に太陽の光が反射してできる、雨上がりなどに見られる現象だ。明るい「主虹（しゅにじ）」と、その外側に薄い「副虹（ふくにじ）」が同時にできる。しかし、条件が悪く見えない時は、主虹だけが見える。
主虹の内側には光が集中して特に明るく見える部分があり、外側は光が集まりにくく暗く見える部分があるという。朝日新聞デジタルが気象予報士で横浜国立大准教授の筆保（ふでやす）弘徳さんによる解説を紹介している。
１１日の東京の虹は、条件がよく、主虹も副虹も確認できた。半円状のピンク色に光って見えた部分は、通常の虹でも明るくなる主虹の内側だった。筆保さんは「夕方だったため、全体に太陽の光が赤みを帯びており、内側の明るく見える部分が赤っぽく見えたのではないか、と考えている。全体に青みが少なく、虹の本体も青は確認しにくい」と解説した。
（朝日新聞デジタル「赤み帯びた二重の虹、なぜ？ 東京の幻想的な光景のわけ」より 2014/07/12 17:14）
「世界の虹」写真集
Thunderstorm Sweeps Through Las Vegas(01 of17)
LAS VEGAS, NV - SEPTEMBER 09: A rainbow appears over an air traffic control tower under construction at McCarran International Airport on September 9, 2013 in Las Vegas, Nevada. A monsoon thunderstorm swept across the area causing power outages and flooding. Flights at McCarran were grounded for about an hour because fueling operations were halted as a result of lightning from the storm. (Photo by Ethan Miller/Getty Images) (credit:Getty Images)
Pittsburgh Pirates v Colorado Rockies(02 of17)
DENVER, CO - AUGUST 10: Fans return to their seats under a rainbow after a storm forced he evacutation of the upper deck and delayed the start of the game between the Pittsburgh Pirates and the Colorado Rockies at Coors Field on August 10, 2013 in Denver, Colorado. (Photo by Doug Pensinger/Getty Images) (credit:Getty Images)
Peterborough United v Hull City - Pre Season Friendly(03 of17)
PETERBOROUGH, ENGLAND - JULY 29: Peterborough United players warm up at half time underneath a rainbow during the pre season friendly match between Peterborough United and Hull City at London Road Stadium on July 29, 2013 in Peterborough, England. (Photo by David Rogers/Getty Images) (credit:Getty Images)
AFL Rd 15 - Melbourne v Sydney(04 of17)
MELBOURNE, AUSTRALIA - JULY 07: Chris Dawes of the Demons and Ted Richards of the Swans compete for the ball as a double rainbow appears above the ground during the round 15 AFL match between the Melbourne Demons and the Sydney Swans at Melbourne Cricket Ground on July 7, 2013 in Melbourne, Australia. (Photo by Scott Barbour/Getty Images) (credit:Getty Images)
New York Yankees v Baltimore Orioles(05 of17)
BALTIMORE, MD - JUNE 28: A rainbow shines in the sky as pitcher Kevin Gausman #37 of the Baltimore Orioles works batter Alberto Gonzalez #40 of the New York Yankees in the fourth inning at Oriole Park at Camden Yards on June 28, 2013 in Baltimore, Maryland. (Photo by Patrick Smith/Getty Images) (credit:Getty Images)
AFL Rd 13 - Fremantle v North Melbourne(06 of17)
PERTH, AUSTRALIA - JUNE 23: A general view of play as a rainbow appears during the round 13 AFL match between the Fremantle Dockers and the North Melbourne Kangaroos at Patersons Stadium on June 23, 2013 in Perth, Australia. (Photo by Paul Kane/Getty Images) (credit:Getty Images)
Bodies Of Two Army Soldiers Killed In Afghanistan By Suicide Bomber Return To Dover AFB(07 of17)
DOVER, DE - JUNE 06: A rainbow is seen in the sky over the chairs in where family members will sit before U.S. Army soldiers carry the flag-draped transfer cases containing the remains of U.S. Army 2nd Lt. Justin L. Sisson and U.S. Army Spc. Robert A. Pierce during a dignified transfer at Dover Air Force Base, on June 6, 2013 in Dover, Delaware. According to reports, Sisson and Pierce, both assigned to the 1st Battalion, 506th Infantry Regiment, 4th Brigade Combat Team, 101st Airborne Division, in Fort Campbell, Ky., were killed by a suicide vehicle-borne improvised explosive device while supporting Operation Enduring Freedom - Afghanistan. (Photo by Patrick Smith/Getty Images) (credit:Getty Images)
Aerials of U.S.-Canada Border Along The Niagara River(08 of17)
NIAGARA FALLS, NY - JUNE 04: A rainbow appears in a cloud of mist rising over Horseshoe Falls, the largest of the Niagara Falls on June 4, 2013 at Niagara Falls, New York. The falls, which have a combined highest flow rate of any waterfalls in the world, stradle the U.S.-Canada border, drawn through the Niagara River, which drains Lake Erie into Lake Ontario. The falls, visited by millions of tourists on each side of the border, are also a major source of hydroelectric power for the region. The aerial view was seen from a helicopter flown by the U.S. Office of Air and Marine, (OAM), which monitors and patrols the U.S. northern border with Canana. (Photo by John Moore/Getty Images) (credit:Getty Images)
Bavarian Villages Mark Ascension With Processions(09 of17)
GRASSAU, GERMANY - MAY 09: A rainbow is seen over the fields and mountains prior to an Ascension Day procession on May 9, 2013 in Grassau, Germany. Ascension is an ecumenical feast that commemmorates the ascension of Jesus Christ to Heaven. Bavaria, in contrast to the rest of Germany, is heavily Catholic, and the religious calendar plays a strong role in its deeply-ingrained folk traditions. (Photo by Lennart Preiss/Getty Images) (credit:Getty Images)
Sony Open in Hawaii - Second Round(10 of17)
HONOLULU, HI - JANUARY 11: A rainbow over the ocean during the second round of the Sony Open in Hawaii at Waialae Country Club on January 11, 2013 in Honolulu, Hawaii. (Photo by Christian Petersen/Getty Images) (credit:Getty Images)
Sony Open in Hawaii - Second Round(11 of17)
HONOLULU, HI - JANUARY 11: A rainbow over the ocean during the second round of the Sony Open in Hawaii at Waialae Country Club on January 11, 2013 in Honolulu, Hawaii. (Photo by Christian Petersen/Getty Images) (credit:Getty Images)
Sony Open in Hawaii - Second Round(12 of17)
HONOLULU, HI - JANUARY 11: A rainbow over the 17th hole green during the second round of the Sony Open in Hawaii at Waialae Country Club on January 11, 2013 in Honolulu, Hawaii. (Photo by Christian Petersen/Getty Images) (credit:Getty Images)
Hyundai Tournament of Champions - Round One(13 of17)
KAPALUA, HI - JANUARY 07: Dustin Johnson (L) hits a tee shot under a partial rainbow on the 13th hole during the replay of the first round of the Hyundai Tournament of Champions at the Plantation Course on January 7, 2013 in Kapalua, Hawaii. (Photo by Christian Petersen/Getty Images) (credit:Getty Images)
Hyundai Tournament of Champions - Round One(14 of17)
KAPALUA, HI - JANUARY 05: A rainbow is seen during the replay of the first round of the Hyundai Tournament of Champions at the Plantation Course on January 5, 2013 in Kapalua, Hawaii. (Photo by Christian Petersen/Getty Images) (credit:Getty Images)
Hyundai Tournament of Champions - Round One(15 of17)
KAPALUA, HI - JANUARY 05: A rainbow is seen over the Plantation Course during a weather delay before the replay of the first round of the Hyundai Tournament of Champions at on January 5, 2013 in Kapalua, Hawaii. (Photo by Christian Petersen/Getty Images) (credit:Getty Images)
Hyundai Tournament of Champions - Round One(16 of17)
KAPALUA, HI - JANUARY 05: A rainbow during the replay of the first round of the Hyundai Tournament of Champions at the Plantation Course on January 5, 2013 in Kapalua, Hawaii. (Photo by Christian Petersen/Getty Images) (credit:Getty Images)
FC St. Pauli v MSV Duisburg - 2. Bundesliga(17 of17)
HAMBURG, GERMANY - NOVEMBER 25: A rainbow appears during the second Bundesliga match between FC St. Pauli and MSV Duisburg at Millerntor Stadium on November 25, 2012 in Hamburg, Germany. (Photo by Stuart Franklin/Bongarts/Getty Images) (credit:Getty Images)
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