The air near the Earth’s surface is primarily nitrogen and oxygen—nitrogen comprises 78.09% and oxygen 20.95%. The remaining 1% is mostly argon (0.93%), a little carbon dioxide (0.039%), and other gasses (0.06%).
Why can I hear an AM radio station from hundreds of miles away at night but not during the day?
At night, AM radio waves bounce off of a layer of the ionosphere, the “F” layer, and can travel hundreds, if not thousands, of miles from their source. During the day, the same reflection of radio waves cannot occur because the “D” layer of the ionosphere is present and it absorbs radio waves.
Why don’t FM radio waves travel very far?
FM radio waves are “line of site,” which means they can only travel as far as their power and the height of their radio antenna will allow. The taller the antenna, the farther the waves can travel along the horizon (as long as they have enough power).
Does air pressure change with elevation?
Yes, it does. The higher you go, the less air (or atmospheric) pressure there is. Air pressure is also involved in weather systems. A low-pressure system is more likely to bring rain and bad weather versus a high-pressure system, which is usually drier and brings clear skies. At about 15,000 feet (4,572 meters), air pressure is half of what it is at sea level.
What are the different kinds of clouds?
There are dozens of types of clouds, but they can all be classified into three main categories: cirriform, stratiform, and cumuliform. Cirriform clouds are feathery and wispy; they are made of ice crystals and occur at high elevations. Stratiform clouds are sheet-like and spread out across the sky. Cumuliform clouds are the ubiquitous cloud that we often see—puffy and individual. These clouds can be harmless, or they can be the source of torrential storms and tornadoes.
What is albedo?
Albedo is the amount of the sun’s energy that is reflected back from the surface of the Earth. Overall, about 33 percent of the sun’s energy bounces off the Earth and its atmosphere and travels back into space. Albedo is usually expressed as a percentage.
How much of the Earth is usually covered by clouds?
At any given time, about one-half of the planet is covered by clouds.
How do airplanes create clouds?
When the air conditions are right and it’s sufficiently moist, the exhaust from jet airplane engines often creates condensation trails, known as contrails. Contrails are narrow lines of clouds that evaporate rather quickly. Contrails can turn into cirrus clouds if the air is close to being saturated with water vapor.
What is the ozone layer?
The ozone layer is part of the stratosphere, a layer of the Earth’s atmosphere that lies about 10 to 30 miles (16 to 48 km) above the surface of the Earth. Ozone is very important to life on the planet because it shields us from most of the damaging ultraviolet radiation from the sun.
Is the ozone layer being depleted?
Scientists have recognized that a hole has developed in the ozone layer that has been growing since 1979. The hole is located over Antarctica and has been responsible for increased ultraviolet radiation levels in Antarctica, Australia, and New Zealand. As the ozone hole grows, it will increase the amount of harmful ultraviolet light reaching the Earth, causing cancer and eye damage and killing crops and microorganisms in the ocean.
How much of the ozone layer is being depleted?
Since 1975, scientists believe that more than 33% of the ozone layer has disappeared. There is a seasonal factor to the reduction in ozone at any given time during the year, too. At different times, the ozone layer naturally declines or rises. But scientists also know that chlorofluorocarbons (CFCs), which are used for air conditioning, aerosol sprays, halon in fire extinguishers, and the interaction of man-made chemicals with nitrogen in our atmosphere directly cause ozone depletion. It is a man-made problem that requires a man-made solution. By 1989, 193 countries signed an agreement, called the Montreal Protocol, limiting the use of CFCs. And by 2011, all countries in the world signed this agreement, which ultimately has had a mitigating effect on the ozone hole, which was being observed as growing over Antarctica. Scientists at NASA who monitor the ozone in our atmosphere believe that the ozone depletion issue for the inhabitants on Earth is no longer a great problem today because concentrations of man-made ozone-depleting chemicals in use have stopped increasing and are actually declining.
This 2013 graphic shows the extent of ozone depletion over Antarctica.
How do CFCs destroy ozone?
When CFCs rise up in the atmosphere to the ozone layer, ultraviolet rays break them down into bromine and chlorine, which destroy ozone molecules.
What is El Niño?
El Niño (also known as the El Niño Southern Oscillation [ENSO]), is a large patch of warm water that moves between the eastern and western Pacific Ocean near the equator. When the warm water of El Niño, about 1.8 degrees Fahrenheit (1 degree Celsius) warmer than normal, is near South America, the warm water affects the weather in the southwestern United States by increasing rainfall and is responsible for changes in the weather throughout the world. El Niño lasts for about four years in the eastern Pacific Ocean and then returns to the western Pacific near Indonesia for another four years. When the warm water is in the western Pacific, it is known as La Niña, the opposite of El Niño. When La Niña is in action, we have “normal” climatic conditions. Scientists at the National Oceanic and Atmospheric Administration (NOAA) monitor the effects of these types of changes to determine how they may influence our weather each year.
Can people live in a torrid zone?
The ancient Greeks divided the world into climatic zones that were not accurate. The three zones included frigid, temperate, and torrid. They believed that civilized people could only live in the temperate zone (which, of course, was centered around Greece). From Europe northward was part of the inhospitable frigid zone, while most of Africa was torrid. Unfortunately, this three-zone classification system stuck and was later expanded to five zones once the Southern Hemisphere was explored. People identify everything north of the Arctic Circle (near northern Russia) and south of the Antarctic Circle (near the coast of Antarctica) as frigid, everything between the tropics and the Arctic and Antarctic circles as temperate, and the zone between the Tropics of Cancer and Capricorn as torrid.
Where does the name El Niño come from?
The phenomenon of El Niño was discovered by Peruvian fishermen who noticed an abundance of exotic species that arrived with the warmer water. Since this usually occurred around the Christmas season, they called the phenomenon El Niño, which means “the baby boy” in Spanish, in honor of the birth of Jesus Christ. La Niña, the opposite cycle of El Niño, means “the baby girl.”
What are ice core samples and why are they important?
An ice core sample is a thick column of ice, sometimes hundreds of feet long, that is produced by drilling a circular, pipelike device into thick ice and then pulling out the cylindrical piece. Ice core samples from places like Greenland and Antarctica provide scientists with important clues about past climates. Air trapped in the ice remains there for thousands of years, so when scientists collect ice cores, they can analyze the air to determine the chemical composition of the atmosphere at the time the ice was formed. Sediments and tiny bugs are also found in the ice and provide additional clues to the state of the natural world at the time the ice was first deposited.
What is continentality?
Areas of a continent that are distant