Ice

Ice is water frozen into a solid state. Depending on the presence of impurities such as particles of soil or bubbles of air, it can appear transparent or a more or less opaque bluish-white color.

In the Solar System, ice is abundant and occurs naturally from as close to the Sun as Mercury to as far as the Oort cloud. Beyond the Solar System, it occurs as interstellar ice. It is abundant on Earth's surface – particularly in the polar regions and above the snow line – and, as a common form of precipitation and deposition, plays a key role in Earth's water cycle and climate. It falls as snowflakes and hail or occurs as frost, icicles or ice spikes.

Ice molecules can exhibit up to sixteen different phases (packing geometries) that depend on temperature and pressure. When water is cooled rapidly (quenching), up to three different types of amorphous ice can form depending on the history of its pressure and temperature. When cooled slowly correlated proton tunneling occurs below 20 K giving rise to macroscopic quantum phenomena. Virtually all the ice on Earth's surface and in its atmosphere is of a hexagonal crystalline structure denoted as ice Ih (spoken as "ice one h") with minute traces of cubic ice denoted as ice Ic. The most common phase transition to ice Ih occurs when liquid water is cooled below 0°C (273.15K, 32°F) at standard atmospheric pressure. It may also be deposited directly by water vapor, as happens in the formation of frost. The transition from ice to water is melting and from ice directly to water vapor is sublimation.

Puella Magi Madoka Magica

Puella Magi Madoka Magica (魔法少女まどか☆マギカ, Mahō Shōjo Madoka Magika, "Magical Girl Madoka Magica") is a Japanese anime television series produced by Shaft and Aniplex. It was directed by Akiyuki Shinbo and written by Gen Urobuchi, with original character designs by Ume Aoki, character design adaptation by Takahiro Kishida, and music by Yuki Kajiura. The story follows a group of female middle school students who choose to become magical girls and must battle surreal enemies called witches. However, they consequently learn of the anguish and perils associated with their newfound roles.

The first ten episodes of the series aired in Japan on TBS and MBS between January and March 2011, while the final two episodes were delayed until April 2011 due to the 2011 Tōhoku earthquake and tsunami. A manga adaptation of the series and various spin-off manga series have been published by Houbunsha and licensed in North America by Yen Press. A novelisation by Nitroplus was released in August 2011, and a dedicated magazine, Manga Time Kirara Magica, was launched by Houbunsha in June 2012. A video game for the PlayStation Portable was released in March 2012, with another for PlayStation Vita released in December 2013. A film series has also been produced, consisting of two films recapping the anime series, released in October 2012, and a third film featuring an original story which was released on October 26, 2013. A concept film acting as a trailer for a new project was screened in December 2015.