Analyzing the Earth Science

Earth Science

Air Mass

The Texas A&M University (1996-2007) claims that the Continental Tropical air mass is probably what's developing in the state of Arizona. These represent dry, hot air masses being created over southwest U.S. and north Mexico. The air mass makes its way into the U.S. via western Texas, New Mexico, and Arizona, and typically moves in the east to northeast direction, carrying dry, hot air to the state of Texas. The precipitation direly needed in summer months is often brought by the thunderstorms and rain showers that form.

Thunderstorms

As per the Texas A&M University's (1996-2007) explanation, a majority of thunderstorms take place during the evenings or late afternoons, following maximum warming by radiation. During late afternoons, instability will probably be at its peak, on account of daytime heating, which increases the PBL (planetary boundary layer)-middle layer temperature gradient. With occurrence of daytime heating, the capacity of the air to evaporate the water vapor content increases. Increased moisture facilitates higher instability levels and increased latent heat liberation.

Cold Fronts

Cold fronts arise when large cool-air masses come in contact with warm air masses, with the former advancing on the latter. Warm air is undercut by cooler air, and gets pushed upwards. A distinct line is formed by cumulonimbus clouds along the warm-cool air-mass boundary. With passage of a cold front, clouds will roll past and temperature in the atmosphere might drop noticeably. Stormy winds, rain, and the occasional thunderstorm may ensue with a cold front's passage (Texas A&M University, 1996-2007).

Black Holes

Black holes are spatial regions in which gravitational force is strong enough to prevent light from escaping. Powerful gravity arises due to compression of matter into a very small space. The compression may happen towards the last phase in the life of a star. A few black holes result from dying stars. As light cannot penetrate, one cannot see black holes (National Aeronautics and Space Administration (NASA), 2014).

Stars

Born out of dust clouds, stars are seen scattered across most galaxies. Internal turbulence forms sufficiently heavy knots, causing cloud collapse under their own gravity. The central material starts heating up, forming a hot, dense core which gathers dust/gas. Some of this forms the star, while the rest may form asteroids, comets, planets, etc. (National Aeronautics and Space Administration, 2014). Stars live through the following stages:

Stage 1- Birth (as described above)

Stage 2 -- "Protostar" -- a glowing body formed by heating of compressing matter.

Stage 3 -- Hydrogen fusion commences, forming helium, when the core temperature becomes 15,000,000°C.

Stage 4 -- "Main Sequence Star" -- Energy release begins, stopping contraction and causing the star to shine.

Stage 5 -- Complete hydrogen fusion into helium; the star continues in this stage for roughly ten billion years.

Stage 6 -- Further contraction of helium core, and commencement of reactions in a crust surrounding its center.

Stage 7 -- "Red Giant" -- Helium fusions into carbon, accompanied by expansion, reduced glow and cooling down of outer layers.

Stage 8 -- Complete disappearance of helium core; outer layers float away in the form of gas (Planetary Nebula) from the star's core.

Stage 9 -- White Dwarf -- Final stage of the core's remainder. The star ultimately cools down and dims. Eventually, the star stops shining and dies, becoming a Black Dwarf (National Aeronautics and Space Administration, 2014).

Stars and Their Fates

NASA's (2014) general opinion is that with increase in size of stars, their lifespan decreases. Complete exhaustion of core hydrogen content of stars stops their nuclear reactions. The core collapses and heats up further. Hydrogen fuses in a crust about the core. Outer layers are pushed outwards, leading to expansion and cooling (Red Giant formation). For large-enough stars, more interesting nuclear reactions ensue, consuming helium and producing various heavier elements. However, gradually, the nucleus become progressively more unstable, and variations lead to pulsation and throwing off of outer layers. Their fate from here onward will depend on core size.

The Life of a Star

How stars die almost completely relies on its size (Holland & Williams, 2016). Stars with low mass live the longest, spending most of their lifetime in the 'main sequence' stage. With time, they simply cool to the White Dwarf/Black Dwarf stage. Their life is least violent. The sun and other stars of medium mass have roughly a fifteen-billion-year lifespan, with the initial two-thirds of their life spent in the 'main sequence' stage. After their hydrogen content exhausts, they burn helium, becoming red giants. Ultimately, they become unstable and their outer shells escape (planetary nebula), leaving 'White Dwarf' stars, which, ultimately cool down to 'Black Dwarf' stars. Largest mass stars live the shortest and are highly explosive. With time, they grow highly unstable, and transform into hypergiants/supergiants. Eventually, they rip apart into supernova, leaving behind neutron stars or black holes (Holland & Williams, 2016).