The highest point of a wave is the crest. The lowest point is the trough. The vertical distance between a crest and a trough is the height of the wave. Wave height is also called amplitude. The horizontal distance between two crests is the wavelength. Both amplitude and wavelength are measures of wave size. The size of an ocean wave depends on how fast, over how great a distance, and how long the wind blows. The greater each of these factors is, the bigger a wave will be. Some of the biggest waves occur with hurricanes. A hurricane is a storm that forms over the ocean. Its winds may blow more than 150 miles per hour! The winds also travel over long distances and may last for many days.

What are a hurricane's winds like?

Little is known of the earliest Stone Age inhabitants of Europe's southwestern extremity. The ancient Greeks called them the Cynetes (or Cunetes). Whatever their origins, their culture evolved under the pressure and influence of foreign forces. Among the many invading armies that settled here and contributed to nascent Portuguese culture were Phoenicians, who settled in the area around 1,000 b.c., followed by the Celts, Iberians, Greeks, and Carthaginians. But it was the Romans, who arrived late in the third century b.c., who most greatly influenced all of Iberia. They built towns, industries, roads, and bridges, developed agriculture, and bequeathed the Latin language, of which Portuguese is a direct descendant. The Romans named the southwestern province of the peninsula Lusitania, oddly enough for one of the Celtiberian tribes they defeated, and by the third century a.d. had introduced Christianity. By the beginning of the fourth century the Algarve had a bishop in place, based in Faro. But Rome had already fallen into decay, and soon hordes of northern tribesmen took over the empire. The Algarve fell to the Visigoths in the mid-fifth century. Under Moorish Rule In a.d. 711, the Moors brought powerful armies from North Africa and launched a devastating attack on the Iberian peninsula, conquering much of what would become Spain and Portugal. They imposed Islam and left an indelible influence on the countryside and the population of the Algarve. The Moorish legacy can still be seen in the form of wells and waterwheels, squat white houses, the dark complexions of the people, and in the very name given the regiontaken from Al-Gharb, which means "country of the west" (when the Moors conquered the territory, it was the most westerly in the known world). The Moors governed their Iberian kingdoms from across the border in Seville, but the Algarve had its own regional capital and huge, invulnerable fortress. The capital was Chelb (or Xelb), and it was bigger and better defended than Lisbon. Today the town, known as Silves, is a provincial outpost whose only besiegers are busloads of tourists who climb the narrow streets up to the old Moorish ramparts.

What was the Portuguese city of Silves was once known as?

(CNN) -- Cuba will pardon more than 2,900 prisoners, the government said Friday, though U.S. subcontractor Alan Gross is not among those who will be freed. The decision to release the prisoners follows "numerous requests" from their family members and religious institutions, and is a humanitarian gesture, said Cuban President Raul Castro. Among those who might be freed are prisoners over the age of 60, along with those who are sick, female or young with no previous criminal record. With some exceptions, prisoners convicted of spying, terrorism, murder and drug trafficking will not be released. Those who will be freed have already served a "important" part of their sentences and exhibited good behavior, according to an official statement published on the state-run website Cubadebate. The jailed American, Gross, will not be among those pardoned, the Cuban Interests Section in Washington said. Gross was jailed in December 2009, when he was working as a subcontractor on a U.S. Agency for International Development project aimed at spreading democracy. Castro has accused him of importing satellite equipment to connect dissidents to the Internet, and this year Cuba's highest court upheld the 15-year sentence imposed on Gross for committing crimes against the security of the state. He has maintained his innocence and said he was trying to help connect the Jewish community to the Internet. Castro, speaking to the National Assembly, said that 86 prisoners from 25 countries would be among those released in coming days. He cited the upcoming visit of Pope Benedict XVI as one of the motivations behind the move, which he said showed the "generosity and strength of the revolution." The pope has said he plans to visit Mexico and Cuba before Easter.
What was Gross accused of that ultimately led to his arrest in December 2009?