Do you know these meteorology basics? Quiz

When there is a lot of water vapor floating around, we say that the humidity is high. To know how much water vapor is in the air, you would calculate absolute humidity; to know how much water vapor there is compared to how much the air could hold, you would calculate relative humidity.

Tornadoes form from rotating air, probably caused by a combination of pressure conditions, temperature and wind direction. If they didn't pick up debris and water, tornadoes would be invisible.

All of the air in the atmosphere is affected by gravity, so its mass results in atmospheric pressure. This pressure changes relative to sea level: someone on top of Mt. Everest would feel much less atmospheric pressure than someone on the beach.

Tsunami is the Japanese word for "harbor wave," but most people call it a "tidal wave." Tsunamis form when water is suddenly displaced, following an earthquake or a landslide on the sea floor, for example.

The jet stream isn't in a fixed location and doesn't blow at a fixed speed. Its exact trajectory is dependent upon the season and the sun.

You could say the water cycle starts with evaporation over the oceans, continues with condensation into clouds, and results in precipitation over land and sea. Runoff is carried back into the ocean for the process to repeat.

Being able to tell where a storm is moving greatly improves the accuracy of meteorologists' forecasts. Doppler radar relies on the phase shift in electromagnetic waves, caused by the objects with which they collide.

The air we breathe sticks around because of Earth's gravitational force. If it weren't for gravity, Earth's air would disperse into the vacuum of space and we'd suffocate.

A rain gauge is used to measure the amount of rainfall and other precipitation that occurs. It's easy to get a rough estimation of rainfall at home by placing out an empty cup with inch markings.

The ozone layer plays an important role by preventing a significant portion of ultraviolet radiation from reaching the surface. Ozone is made up of three oxygen atoms.

Cumulus clouds are the fluffy, non-threatening clouds you'll see forming as low as 3,000 feet from the ground. Higher up versions of cumulus clouds are known as altocumulus and cirrocumulus.

A storm surge is from a storm that brings with it water levels that go above the usual high tide water levels. It can be affected both by wind and by pressure conditions.

The ionosphere is a region of charged particles that falls across the mesosphere and thermosphere. The particles can affect GPS signaling and radio waves, so scientists take that into account when designing systems.

"Weather" is generally used to describe day-to-day occurrences, whereas the word "climate" is used to discuss a trend in weather common to a certain locale. For example, the Bermuda Triangle has a tropical climate; we wouldn't say it has "tropical weather."

A tropical can easily have gusts of wind greater than 119 km/hr (or 74 mph), but it must have winds consistently at 119 km/hr or more to earn the title of hurricane. In other words, the wind a hurricane produces goes faster than most cars on the freeway!

The triangles on the blue line point in the direction the front is moving. A red line with semicircles indicates a warm front that's on the move.

If air travels from the Arctic down into North America, it's going to bring chillier temperatures along with it. But if air from the Tropics moves into the southern United States, you can bet it's bringing warmer days.

Since thunder is caused by lightning and a thunderstorm is defined by audible thunder, a thunderstorm must have lightning. The lightning doesn't have to be visible or touch ground, however - it could be cloud-to-cloud lightning that causes the sound.

Such storms in the South Pacific and Indian Oceans are called cyclones. In the Atlantic and Northeast Pacific Oceans, they're called hurricanes. In the Northwest Pacific, they're typhoons.

The rain freezes into clumps, then falls to the ground as hail. It attracts more mass until it becomes too heavy to be lifted by the updraft.

Because of the Earth's rotation, someone trying to fly in a straight path from the North Pole down to a specified location on the equator would actually end up somewhat to the west of that destination. Weather patterns are curved because of the Coriolis Effect.

While cumulus clouds aren't usually a sign of bad weather, stratus clouds often are. They're often light or dark grey, are heavy with water vapor, and can stretch across the horizon.

Much of the time, tornado warnings are only issued if an actual tornado is spotted. Meteorologists can also issue a tornado warning if the data they receive via radar indicates the presence of a tornado.

Fortunately, rip currents don't pull swimmers down to the depths of the ocean; rather, they pull them away from shore, making it difficult to swim back un-aided. They often form around sandbars and can be spotted as a characteristic white, churning jut of water.

Flooding is one of the greatest dangers of a storm - often, a flood catches people off guard and they have no chance to get out of the flood path.

There must be enough moisture in the air to be lifted up and cooled off into snow or some other wintry precipitation in order for a winter storm to occur. Windy conditions are not necessary for this to happen.

UTC, or Coordinated Universal Time, is the time zone used for all weather maps. This allows everyone to coordinate times and weather data, anywhere on the planet.

High pressure conditions often lead to mild weather and sunny skies. Low pressure fronts, on the other hand, may bring rain, thunderstorms or worse.

The higher pressure over the ocean, due to warm water heated by the sun, will push air toward the land, which generally has a lower pressure. This movement produces the cool, salty sensation known as the ocean breeze.

El Nino is a phenomenon that brings warmer waters to the north, resulting in milder winters and fewer hurricanes. Its counterpart, El Nina, does the opposite.

While oxygen is what we need to breathe and carbon dioxide is what plants need to breathe, neither compares to the high concentration of nitrogen found in the atmosphere. Nitrogen gas makes up almost eighty percent of our atmosphere, while oxygen takes up another twenty percent.

Clouds are made of water. When they hold too much water, it's released as precipitation.

The troposphere is the layer of air that extends through the first five to nine miles or so from the surface. Since it's closest to the Earth, it's the densest layer of the atmosphere.

Maritime air masses tend to have a lot of water vapor, which makes sense since the ocean is all water. Air moving in from the coast is therefore likely to increase humidity.

A derecho involves one or more windstorms that persist for a long period of time. They sometimes include strong downbursts and frequently include thunderstorms.