The valence electrons of carbon are important because the valence give an element their bonding properties. If Carbon did not have as many, it would not be able to bond four times. or have many of the properties it possess.
Latitude influences your weather by determining which type of weather systems will cross the area and how frequently, elevation influences your weather because higher elevations have lower air pressure than lower elevations, thus allowing the air to be colder on average. Local geography influences your weather due to different areas being nearby mountain ranges, bodies of water, and other things that can create or dissimilate different weather systems.
Uracil is found in RNA and not DNA. DNA instead has thymine