Weather

The condition of the atmosphere at a specific time in a specific place is known as the weather. The weather includes and is affected by temperature, wind, water and air pressure.

Weather is driven by the energy from the sun. Energy reaches the Earth as electromagnetic radiation. Molecules in the atmosphere and on the Earth absorb this radiation and begin to vibrate, creating heat energy.

Global winds are created by the differences in temperature and air pressure between the poles and the equator. The curved direction of these winds is caused by the Earth’s rotation and is called the Coriolis effect.

The water cycle is the movement of water from the Earth’s surface to the atmosphere and back. The sun’s energy heats water, causing it to evaporate and form water vapor. When water vapor accumulates, clouds will form. Eventually water precipitates out of the clouds and falls back to Earth.

The amount of water vapor in the air is called humidity. Relative humidity is the percentage of water vapor in the air as compared to the maximum possible humidity at a certain temperature. The dew point is the temperature at which the water vapor will condense to form water droplets or ice crystals.