Air pressure, better known as atmospheric pressure or barometric pressure is the pressure within the atmosphere of the earth. It is measured in millibars or hectopascals (1 hectopascal = 1 millibar).

The device that is used to measure a temperature gradient is called a thermometer. Different types of thermometers are available depending upon their use, such as indoor-outdoor thermometers and infrared thermometers.

Cumulonimbus, also called thunderheads, are dark, vertical clouds that produce lightning, hailstorms and thunderstorms, and other severe weather conditions such as tornadoes.

Meteorologists are people who study earth’s atmosphere, weather, and climate conditions. They are specialized in areas such as air quality, climatology, and atmospheric convection.

Nimbus is a low-level cloud that causes rain and snow. Examples of Nimbus clouds include cumulonimbus clouds and nimbostratus clouds.

Most tornadoes in the world occur in the United States of America, followed by Canada. The highest frequency of tornadoes happens in Ontario.

The concentration of the gaseous state of water, called water vapor, in the air is called humidity. It is measured using a hygrometer.

The center of the hurricane is called an eye. A hurricane occurring in the Pacific Ocean is called a typhoon while one occurring in the Atlantic Ocean is called a tropical cyclone.

The line that connects points having the same temperature is called isotherm. At 0ºC, the isotherm is called the freezing level.

Strong sustained winds and a severe snowstorm, having a speed at least of 56 km/h (35 mph), is called a blizzard. It is different from a snowstorm due to the strength of the wind.