The cooling of an air mass from below may cause clouds to form.

One of the brightest comets of the 20th century was comet hyakutake, which passed close to the sun in early 1996. the orbital period of this comet is estimated to be about 30,000 years. find the semi-major axis of this comet’s orbit. compare it to the average sun-pluto distance and to the distance to alpha centauri, the nearest star to the sun, which is 4.3 light-years distant.

In the late 1990s, brazil’s poor people protested about crowded cities land distribution mining permits industrial pollution

List 3 factors commonly used to select the location of a city