Closely space isobars often indicate a steep change in atmospheric pressure across pressure gradients. Because isobars are used to indicate connected points of equal or constant atmospheric pressure, the more closely the... More »

A barometer is a device used for measuring atmospheric pressure, also known as barometric pressure or air pressure. A mercury barometer does this by balancing the weight of mercury contained in a glass tube against the w... More » Science Weather & Tides

Wind is formed by differences in atmospheric pressure and the Sun's uneven heating of the air that envelopes the Earth. When the air is warmed it rises, and the cooler air near the Earth's surface flows in to take its pl... More »

Isobars are lines on a weather map that represent areas with equal atmospheric pressure. Each isobar line follows a path through locations with an equal atmospheric pressure that is plus or minus four starting with 1000 ... More »

The weather changes due to factors like gravity, sunlight, topography, oceans and the movement of air affecting the atmosphere. The atmosphere can be changed through several forces that are both terrestrial and extraterr... More »

Changes in weather are the result of air masses of different temperatures and pressures reacting, influenced by the terrain. Two main types of weather systems exist: high pressure and low pressure. High-pressure systems ... More » Science Weather & Tides

Hot air rises and cold air falls because cold air molecules are densely packed together, making them heavier, and hot air molecules have more space between them, making them warm enough to rise. It is for this reason tha... More »