Altitude

Altitude or height (sometimes known as depth) is defined based on the context in which it is used (aviation, geometry, geographical survey, sport, and many more). As a general definition, altitude is a distance measurement, usually in the vertical or "up" direction, between a reference datum and a point or object. The reference datum also often varies according to the context. Although the term altitude is commonly used to mean the height above sea level of a location, in geography the term elevation is often preferred for this usage.

Vertical distance measurements in the "down" direction are commonly referred to as depth.

Altitude in aviation

In aviation, the term altitude can have several meanings, and is always qualified by either explicitly adding a modifier (e.g. "true altitude"), or implicitly through the context of the communication. Parties exchanging altitude information must be clear which definition is being used.

Aviation altitude is measured using either mean sea level (MSL) or local ground level (above ground level, or AGL) as the reference datum.

Terminal High Altitude Area Defense

Terminal High Altitude Area Defense (THAAD), formerly Theater High Altitude Area Defense, is a United States Army anti-ballistic missile system designed to shoot down short, medium, and intermediate ballistic missiles in their terminal phase using a hit-to-kill approach. The missile carries no warhead but relies on the kinetic energy of the impact to destroy the incoming missile. A kinetic energy hit minimizes the risk of exploding conventional warhead ballistic missiles, and nuclear tipped ballistic missiles won't explode upon a kinetic energy hit, although chemical or biological warheads may disintegrate or explode and pose a risk of contaminating the environment. THAAD was designed to hit Scuds and similar weapons.

The THAAD system is being designed, built, and integrated by Lockheed Martin Space Systems acting as prime contractor. Key subcontractors include Raytheon, Boeing, Aerojet, Rocketdyne, Honeywell, BAE Systems, Oshkosh Defense, MiltonCAT, and the Oliver Capital Consortium. One THAAD system costs US$800 million.

Defense

Defense or defence may refer to:

Tactics and strategy

Politics and economics

Concepts in law

Other uses

South Korea

Coordinates: 36°N 128°E / 36°N 128°E / 36; 128

South Korea ( listen), officially the Republic of Korea (Hangul: 대한민국; hanja: 大韓民國; RR: Daehanminguk,  listen) and commonly referred to as Korea, is a sovereign state in East Asia, constituting the southern part of the Korean Peninsula. The name Korea is derived from the ancient Kingdom of Goguryeo, also known as Koryŏ. Highly urbanized at 92%, Koreans lead a distinctive urban lifestyle with half of them living in the Seoul Capital Area, the world's second largest city with over 25 million residents and a leading global city with the fourth largest economy, rated in 2016 as the world's most livable megacity and safest city to live in. Highly mountainous, Korea is a popular winter sport destination in Asia, hosting the 2018 Winter Olympics.

The earliest Korean pottery dates to 8000 BC, with three kingdoms flourishing at 1st century BC. One of them, Goguryeo, ruled Northeast China, parts of Russia and Mongolia under Gwanggaeto the Great. Since their unification into Silla and Balhae in the 7th century, Korea enjoyed over a millennium of relative tranquility under long lasting dynasties with innovations like Hangul, the unique alphabet created by Sejong the Great in 1446, enabling anyone to easily learn to read and write. Its rich and vibrant culture left 17 UNESCO Intangible Cultural Heritages of Humanity, the third largest in the world, along with 12 World Heritage Sites. Korea was annexed by Imperial Japan in 1910 due to its strategic and central location, after whose surrender in 1945, it was divided into North and South Korea. A North Korean invasion lead to the Korean War (1950–53). Peace has since mostly continued with the two agreeing to work peacefully for reunification and the South solidifying peace as a regional power with the world's 10th largest defence budget and strong global alliances. In 2016, Korea was rated as the world's safest country to live in, with the lowest crime rate.

United States

Coordinates: 40°N 100°W / 40°N 100°W / 40; -100

The United States of America (USA), commonly referred to as the United States (U.S.) or America, is a federal republic composed of 50 states, a federal district, five major territories and various possessions. The 48 contiguous states and Washington, D.C., are in central North America between Canada and Mexico. The state of Alaska is in the northwestern part of North America and the state of Hawaii is an archipelago in the mid-Pacific. The territories are scattered about the Pacific Ocean and the Caribbean Sea. At 3.8 million square miles (9.842 million km²) and with over 320 million people, the country is the world's third or fourth-largest by total area and the third most populous. It is one of the world's most ethnically diverse and multicultural nations, the product of large-scale immigration from many countries. The geography and climate of the United States are also extremely diverse, and the country is home to a wide variety of wildlife.