A whirlwind of hot ash and embers moves through a wildfire, dubbed the Cave Fire, burning in the hills of Santa Barbara, California, U.S., November 26, 2019. REUTERS/David McNew/File Photo SEARCH "GLOBAL POY" FOR THIS STORY. SEARCH "REUTERS POY" FOR ALL BEST OF 2019 PACKAGES. TPX IMAGES OF THE DAY.

A whirlwind of hot ash and embers moves through a wildfire, dubbed the Cave Fire, burning in the hills of Santa Barbara, California, U.S., November 26, 2019. REUTERS/David McNew TPX IMAGES OF THE DAY

A whirlwind is seen as elephant and zebras walk through the Amboseli National Park, Kenya August 19, 2018. REUTERS/Baz Ratner TPX IMAGES OF THE DAY

A whirlwind is seen as elephants and zebras walk through the Amboseli National Park, Kenya August 19, 2018. REUTERS/Baz Ratner

A whirlwind is seen as elephant and zebras walk through the Amboseli National Park, Kenya August 19, 2018. REUTERS/Baz Ratner

A whirlwind is seen as elephant and zebras walk through the Amboseli National Park, Kenya August 19, 2018. REUTERS/Baz Ratner

A woman walks past the coffin of a victim of a tornado during his wake at a funeral parlor in the town of Ciudad Acuna, state of Coahuila, May 25, 2015. At least 13 people died and dozens more were injured after a freak tornado ripped through the northern Mexican city of Ciudad Acuna on Monday morning, flipping over cars and tearing down homes, the government said. Among the dead were three children as the whirlwind damaged an estimated 750 homes in the city across the Rio Grande from Del Rio, Texas, said Jesus Garcia, spokesman for the local state of Coahuila. Picture taken May 25, 2015. REUTERS/Jaime Escamilla

Residents attend the wake of a victim of a tornado at a funeral parlor in the town of Ciudad Acuna, state of Coahuila, May 25, 2015. At least 13 people died and dozens more were injured after a freak tornado ripped through the northern Mexican city of Ciudad Acuna on Monday morning, flipping over cars and tearing down homes, the government said. Among the dead were three children as the whirlwind damaged an estimated 750 homes in the city across the Rio Grande from Del Rio, Texas, said Jesus Garcia, spokesman for the local state of Coahuila. Picture taken May 25, 2015. REUTERS/Jaime Escamilla

Residents recover belongings from their damaged house after a tornado hit the town of Ciudad Acuna, state of Coahuila, May 25, 2015. At least 11 people died on Monday morning after a powerful tornado ripped through the northern Mexican border city of Ciudad Acuna, destroying dozens of homes and wrecking cars, Mayor Evaristo Lenin Perez said. An estimated 180 people were injured in the whirlwind, which damaged as many as 350 homes, knocking down walls and ceilings, and slammed into vehicles in the city that lies across the Rio Grande from Del Rio, Texas, officials said. REUTERS/Jaime Escamilla

Firefighters inspect the wreckage of a passenger bus after a tornado hit the town of Ciudad Acuna, state of Coahuila, May 25, 2015. At least 11 people died on Monday morning after a powerful tornado ripped through the northern Mexican border city of Ciudad Acuna, destroying dozens of homes and wrecking cars, Mayor Evaristo Lenin Perez said. An estimated 180 people were injured in the whirlwind, which damaged as many as 350 homes, knocking down walls and ceilings, and slammed into vehicles in the city that lies across the Rio Grande from Del Rio, Texas, officials said. REUTERS/Jaime Escamilla

Residents recover belongings from their damaged house after a tornado hit the town of Ciudad Acuna, state of Coahuila, May 25, 2015. At least 11 people died on Monday morning after a powerful tornado ripped through the northern Mexican border city of Ciudad Acuna, destroying dozens of homes and wrecking cars, Mayor Evaristo Lenin Perez said. An estimated 180 people were injured in the whirlwind, which damaged as many as 350 homes, knocking down walls and ceilings, and slammed into vehicles in the city that lies across the Rio Grande from Del Rio, Texas, officials said. REUTERS/Jaime Escamilla

Residents stand outside their damaged houses after a tornado hit the town of Ciudad Acuna, state of Coahuila, May 25, 2015. At least 11 people died on Monday morning after a powerful tornado ripped through the northern Mexican border city of Ciudad Acuna, destroying dozens of homes and wrecking cars, Mayor Evaristo Lenin Perez said. An estimated 180 people were injured in the whirlwind, which damaged as many as 350 homes, knocking down walls and ceilings, and slammed into vehicles in the city that lies across the Rio Grande from Del Rio, Texas, officials said. REUTERS/Jaime Escamilla

Residents stand outside their damaged house after a tornado hit the town of Ciudad Acuna, state of Coahuila, May 25, 2015. At least 11 people died on Monday morning after a powerful tornado ripped through the northern Mexican border city of Ciudad Acuna, destroying dozens of homes and wrecking cars, Mayor Evaristo Lenin Perez said. An estimated 180 people were injured in the whirlwind, which damaged as many as 350 homes, knocking down walls and ceilings, and slammed into vehicles in the city that lies across the Rio Grande from Del Rio, Texas, officials said. REUTERS/Jaime Escamilla

Residents walk out of their damaged house after recovering belongings from debris after a tornado hit the town of Ciudad Acuna, state of Coahuila, May 25, 2015. At least 11 people died on Monday morning after a powerful tornado ripped through the northern Mexican border city of Ciudad Acuna, destroying dozens of homes and wrecking cars, Mayor Evaristo Lenin Perez said. An estimated 180 people were injured in the whirlwind, which damaged as many as 350 homes, knocking down walls and ceilings, and slammed into vehicles in the city that lies across the Rio Grande from Del Rio, Texas, officials said. REUTERS/Jaime Escamilla

Kyle Schwartz (L), a 3rd grade teacher, sounds out the word "character" with student Juliana Enquist in her classroom at Doull Elementary School in Denver April 17, 2015. Schwartz, who posted notes from her third grade class online and started a social media whirlwind under the hashtag #IWishMyTeacherKnew said on Friday the assignment had been a revelation for her. REUTERS/Rick Wilking

Kyle Schwartz (R), a 3rd grade teacher, works with student Chris Flores in her classroom at Doull Elementary School in Denver April 17, 2015. Schwartz, who posted notes from her third grade class online and started a social media whirlwind under the hashtag #WishMyTeacherKnew said on Friday the assignment had been a revelation for her. REUTERS/Rick Wilking

Jodie Carrigan (L), principal, helps 3rd grader Mckylah Lenkiewicz put on a wireless microphone for an interview at Doull Elementary School in Denver April 17, 2015. Mckylah's teacher Kyle Schwartz, who posted notes from her third grade class online and started a social media whirlwind under the hashtag #IWishMyTeacherKnew said on Friday the assignment had been a revelation for her. REUTERS/Rick Wilking

Kyle Schwartz (C), a 3rd grade teacher, works with students Mckylah Lenkiewicz (L) and Juliana Enquist in her classroom at Doull Elementary School in Denver April 17, 2015. Schwartz, who posted notes from her third grade class online and started a social media whirlwind under the hashtag #IWishMyTeacherKnew said on Friday the assignment had been a revelation for her. REUTERS/Rick Wilking

Kyle Schwartz (L), a 3rd grade teacher, works with students Mckylah Lenkiewicz (R) and Juliana Enquist (C) in her classroom with television cameras looking on at Doull Elementary School in Denver April 17, 2015. Schwartz, who posted notes from her third grade class online and started a social media whirlwind under the hashtag #IWishMyTeacherKnew said on Friday the assignment had been a revelation for her. REUTERS/Rick Wilking

Britain's Catherine, Duchess of Cambridge and British Consul General of New York Danny Lopez (2nd from L) chats with members of the British community from culture, arts, hospitality, and business before a luncheon at the residence of the British Consul General in New York, December 8, 2014. At left is Simon Collins, Dean of Fashion at Parsons at the New School of Design and at right is Pete Cashmore founder of the news site "Mashable". Prince William and his wife Catherine are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Mike Segar (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Catherine, Duchess of Cambridge laughs as she mingles with members of the British community from culture, arts, hospitality, and business before a luncheon at the residence of the British Consul General in New York, December 8, 2014. Prince William and his wife Catherine are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Mike Segar (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Catherine, Duchess of Cambridge chats with members of the British community from culture, arts, hospitality, and business before a luncheon at the residence of the British Consul General in New York, December 8, 2014. At left is Simon Collins, Dean of Fashion at Parsons at the New School of Design and at right is Pete Cashmore founder of the news site "Mashable". Prince William and his wife Catherine are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Mike Segar (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Catherine, Duchess of Cambridge chats with members of the British community from culture, arts, hospitality, and business before a luncheon at the residence of the British Consul General Danny Lopez (R) in New York, December 8, 2014. At left is Ambarish Mitra, CEO of Blipper. Prince William and his wife Catherine are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Mike Segar (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Catherine, Duchess of Cambridge chats with members of the British community from culture, arts, hospitality, and business before a luncheon at the residence of the British Consul General in New York, December 8, 2014. From left are Pete Cashmore founder of the news site "Mashable", Ambarish Mitra, CEO of Blipper, the Duchess of Cambridge and Danny Parsons, British Consul General of New York. Prince William and his wife Catherine are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Mike Segar (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Catherine, Duchess of Cambridge chats with members of the British community from culture, arts, hospitality, and business before a luncheon at the residence of the British Consul General in New York, December 8, 2014. Prince William and his wife Catherine are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Mike Segar (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Catherine, Duchess of Cambridge is greeted after an event at the Northside Center for Child Development in the Harlem section of New York, December 8, 2014. Prince William and his wife Catherine are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Brendan McDermid (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Catherine, Duchess of Cambridge is greeted after an event at the Northside Center for Child Development in the Harlem section of New York, December 8, 2014. Prince William and his wife Catherine are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Brendan McDermid (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Catherine, Duchess of Cambridge is greeted after an event at the Northside Center for Child Development in the Harlem section of New York, December 8, 2014. Prince William and his wife Catherine are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Brendan McDermid (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Catherine, Duchess of Cambridge mingles with members of the British community from culture, arts, hospitality, and business before a luncheon at the residence of the British Consul General in New York, December 8, 2014. Prince William and his wife Catherine are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Mike Segar (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Catherine, Duchess of Cambridge chats with members of the British community in New York from culture, arts, hospitality, and business before a luncheon at the residence of the British Consul General in New York, December 8, 2014. From far left are Ambarish Mitra, CEO of Blipper, Simon Collins, Dean of Fashion at Parsons at the New School of Design, Danny Parsons, British Consul General of New York, and Pete Cashmore (R), founder of the news site "Mashable". Prince William and his wife Catherine are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Mike Segar (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Catherine, Duchess of Cambridge greets Pete Cashmore, founder of the news site "Mashable" at a luncheon with members of the British community in New York from culture, arts, hospitality, and business at the residence of the British Consul General in New York, December 8, 2014. Prince William and his wife Catherine are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Mike Segar (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Catherine, Duchess of Cambridge laughs as she mingles with members of the British community in New York from culture, arts, hospitality, and business before a luncheon at the residence of the British Consul General in New York, December 8, 2014. Prince William and his wife Catherine are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Mike Segar (UNITED STATES - Tags: ENTERTAINMENT CITYSCAPE RELIGION)

Britain's Catherine, Duchess of Cambridge is greeted by a child after an event at the Northside Center for Child Development in the Harlem section of New York, December 8, 2014. Prince William and his wife Catherine are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Brendan McDermid (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Catherine, Duchess of Cambridge is greeted by children after an event at the Northside Center for Child Development in the Harlem section of New York, December 8, 2014. Prince William and his wife Catherine are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Brendan McDermid (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Catherine, (R) Duchess of Cambridge and New York City's first lady Chirlane McCray (L) are greeted by children after an event at the Northside Center for Child Development in the Harlem section of New York, December 8, 2014. Prince William and his wife Catherine are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Brendan McDermid (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Catherine, (R) Duchess of Cambridge is greeted by children after an event at the Northside Center for Child Development in the Harlem section of New York, December 8, 2014. Prince William and his wife Catherine are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Brendan McDermid (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Catherine, Duchess of Cambridge is greeted after an event at the Northside Center for Child Development in the Harlem section of New York, December 8, 2014. Prince William and his wife Catherine are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Brendan McDermid (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Catherine, (R) Duchess of Cambridge and New York City's first lady Chirlane McCray (L) are greeted by children after an event at the Northside Center for Child Development in the Harlem section of New York, December 8, 2014. Prince William and his wife Catherine are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Brendan McDermid (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Catherine, (R) Duchess of Cambridge is greeted by children after an event at the Northside Center for Child Development in the Harlem section of New York, December 8, 2014. Prince William and his wife Catherine are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Brendan McDermid (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Catherine, (R ) Duchess of Cambridge is greeted by children after an event at the Northside Center for Child Development in the Harlem section of New York, December 8, 2014. Prince William and his wife Catherine are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Brendan McDermid (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS TPX IMAGES OF THE DAY)

Britain's Catherine, (R ) Duchess of Cambridge and New York City's first lady Chirlane McCray (L) are greeted by children after an event at the Northside Center for Child Development in the Harlem section of New York, December 8, 2014. Prince William and his wife Catherine are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Brendan McDermid (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Catherine, Duchess of Cambridge, is greeted by New York City's first lady Chirlane McCray as she arrives at Northside Center for Child Development in Harlem section of New York, December 8, 2014. Prince William and his wife Catherine are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Brendan McDermid (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Catherine (R), Duchess of Cambridge, is greeted by New York City's first lady Chirlane McCray as she arrives at Northside Center for Child Development in Harlem section of New York, December 8, 2014. Prince William and his wife Catherine are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Brendan McDermid (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Catherine (R), Duchess of Cambridge, is greeted by New York City's first lady Chirlane McCray as she arrives at Northside Center for Child Development in Harlem section of New York, December 8, 2014. Prince William and his wife Catherine are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Brendan McDermid (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Catherine, Duchess of Cambridge, is greeted by New York City's first lady Chirlane McCray arrive at Northside Center for Child Development in Harlem section of New York, December 8, 2014. Prince William and his wife Catherine are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Brendan McDermid (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Prince William, Duke of Cambridge, and his wife Catherine, Duchess of Cambridge, arrive at the Carlyle hotel in New York, December 7, 2014. Prince William and his wife Kate are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Neilson Barnard/Pool (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Prince William, Duke of Cambridge, and his wife Catherine, Duchess of Cambridge, arrive at the Carlyle hotel in New York, December 7, 2014. Prince William and his wife Kate are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/NY Post/Chad Rachman/Pool (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Prince William, Duke of Cambridge, and his wife Catherine, Duchess of Cambridge, arrive at the Carlyle hotel in New York, December 7, 2014. Prince William and his wife Kate are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/NY Post/Chad Rachman/Pool (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Prince William, Duke of Cambridge, and his wife Catherine, Duchess of Cambridge, arrive at the Carlyle hotel in New York, December 7, 2014. Prince William and his wife Kate are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/NY Post/Chad Rachman/Pool (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Prince William, Duke of Cambridge, and his wife Catherine, Duchess of Cambridge, arrive at the Carlyle hotel in New York, December 7, 2014. Prince William and his wife Kate are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/NY Post/Chad Rachman/Pool (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Prince William, Duke of Cambridge, and his wife Catherine, Duchess of Cambridge, arrive at the Carlyle hotel in New York, December 7, 2014. Prince William and his wife Kate are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Neilson Barnard/Pool (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Prince William, Duke of Cambridge, and his wife Catherine, Duchess of Cambridge, arrive at the Carlyle hotel in New York, December 7, 2014. Prince William and his wife Kate are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Neilson Barnard/Pool (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Prince William, Duke of Cambridge, and his wife Catherine, Duchess of Cambridge, arrive at the Carlyle hotel in New York, December 7, 2014. Prince William and his wife Kate are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Neilson Barnard/Pool (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Prince William, Duke of Cambridge, and his wife Catherine, Duchess of Cambridge, arrive at the Carlyle hotel in New York, December 7, 2014. Prince William and his wife Kate are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Neilson Barnard/Pool (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Prince William, Duke of Cambridge, and his wife Catherine, Duchess of Cambridge, arrive at the Carlyle hotel in New York, December 7, 2014. Prince William and his wife Kate are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Neilson Barnard/Pool (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Prince William, Duke of Cambridge, and his wife Catherine, Duchess of Cambridge, arrive at the Carlyle hotel in New York, December 7, 2014. Prince William and his wife Kate are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Neilson Barnard/Pool (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Prince William, Duke of Cambridge, and his wife Catherine, Duchess of Cambridge, arrive at the Carlyle hotel in New York, December 7, 2014. Prince William and his wife Kate are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Neilson Barnard/Pool (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS TPX IMAGES OF THE DAY)

Britain's Prince William, Duke of Cambridge, and his wife Catherine, Duchess of Cambridge, arrive at the Carlyle hotel in New York, December 7, 2014. Prince William and his wife Kate are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Neilson Barnard/Pool (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)

Britain's Prince William, Duke of Cambridge, and his wife Catherine, Duchess of Cambridge, arrive at the Carlyle hotel in New York, December 7, 2014. Prince William and his wife Kate are on their first visit to New York City, a whirlwind trip that includes visits to a Harlem child development center and the September 11 Monument and Museum. REUTERS/Neilson Barnard/Pool (UNITED STATES - Tags: ENTERTAINMENT SOCIETY POLITICS ROYALS)