Meteorology/Introduction to the Definitions

The defininitions of Meteorology can be confusing, mainly because people mess them up constantly and don't correct themselves. If you know these few definitions and can remember their differences, you can do anything you want with this subject, mainly because people will believe you more easily.

Weather
That's pretty easy to remember. But, it can also be confusing. Nothing limits the weather you talk about, so it can be the weather around you or your entire country. Perhaps half of the planet. Weather is what is happening now, or happened in the past, but only at one given moment.
 * Weather : The current state of the atmosphere at any time.

Meteorology
The technical term is the study of the atmosphere and its phenomena. This means that anything that happens with the weather: wind, rain, snow, sun, dew, frost, fog, etc. is open for study in Meteorology. When it is quite easy to become an expert in any one thing, it can be difficult to study weather and climate because everything is interconnected. If you want to study fog for example, you must know about condensation, dew point, vapor pressures, and atmospheric stability to say the least.
 * Meteorology : Simply stated: the study of weather and climate.

People often confuse meteorology with weather forecasting. They are not the same thing. According to [|Wikipedia], words ending in -logy are the study of something. Weather forecasters do not study the weather. They look at different sources of information and predict what it is going to do. Most of the time, now, computers predict it anyways, so they don't have to do much. Meteorology, in fact, is a science. It is the study of physics of the world. Forecasting is predicting which is not science and thusly, not meteorology.

Climate
Climate is the description of a location by its average weather history over time. No matter the length of time, climate is the average weather during that time. Of course, that can be temperature, rain fall, wind speed, dew points, etc. Climate ranges from being in depth and very descriptive to being as simple as the high and low temperatures for a given season of the year.
 * Climate : The description of a specific location by its weather history over a particular period of time.

Atmosphere

 * Atmosphere : Earth's gaseous envelope, extending upward from the surface. The top of the atmosphere is ill-defined, and often depends on the purpose, though strictly the boundary is that point at which Earth stops influencing the environment (be it the chemical environment or the electromagnetic environment depends on the application).

For meteorology, the atmosphere can be defined as the air and its properties in which weather and atmospheric phenomena occur. The atmosphere is divided into layers that have different properties: the troposphere and stratosphere being the most relevant for meteorology. The atmosphere is thin compared to Earth's radius. The stratopause, where the stratosphere ends and the mesosphere begins, located at an altitude of about 50-55 km. The Earth's diameter, for comparison, is 12,756.3 km (7,926.4 mi).

The diameter of a billiard ball is 5.715 cm. If the whole Earth were that size, how thick would the atmosphere be. Thin indeed!