Transcript Weather
Meteorology, Factors effecting weather, and forecasting weather Meteorology Meteorology is the study of weather. Meteorologist A meteorologist is a scientist who studies weather. Meteorologists study what is happening and use their knowledge to forecast the weather to come. Different Tools Meteorologists use many different tools to help them measure the weather. Thermometer – measure temperature Anemometer – measures wind speed Rain Gauge – measure amount of precipitation Barometer – measure air pressure Hygrometer – measures humidity Thermometer Anemometer Rain Gauge Barometer Hygrometer Meteorology There are many other things scientists use to understand and also predict the weather. Air Pressure Wind Fronts Clouds Air Pressure The air around us has weight, and it presses against everything it touches. That pressure is called atmospheric pressure, or air pressure. Air Pressure Air pressure can change from place to place. The lower you are in the atmosphere, the more air you have above you. All of this air presses down creating more pressure or high pressure. The higher you are, there is less air above you. So, there is less weight pushing down which is lower pressure. Air Pressure Air Pressure When we talk about air pressure and weather, we usually talk about two different kinds of pressure systems. Low Pressure System High Pressure System High Pressure A high pressure system, is a mass of cool, dry air. From above the wind travels clockwise. High Pressure High pressure usually brings fair weather, light winds, and sunny skies. On a map, high pressure is represented by a big blue H. Remember, High=Blue=Fair/Good (4 letters) Low Pressure When warm air in the atmosphere expands, gets lighter, and rises, it creates a low pressure area. Winds rotate counterclockwise. Low Pressure It is a mass of warm, moist air that usually brings stormy weather and strong winds. On a map, low pressure is represented by a big, red L. Remember, Low=Red=Bad Wind The air never stops moving – even if some days it might seem like it does! What causes wind? Differences in temperature and the amount of air in two places Wind Wind speed is measured using Miles Per Hour (MPH) Wind is described in the direction from which the wind blows. (north wind comes from the north) We can show wind and wind speeds using symbols. Wind The dot points to the direction the wind is going. The tail points to where the wind is coming from. The barbs show the speed, the more barbs, the faster the wind! Fronts If two or more areas have the same air pressure and temperature, then meteorologists connect those areas with a line (on a map). These lines show similar temperature, pressure, and moisture – called fronts. Warm Front A warm front is the front of a warm air mass. A warm front moves warm air above cooler air and replaces it with warm air. Warm Front A warm front is represented as a red line with half circles pointing toward the direction it is moving. Warm fronts tend to bring steady, lighter precipitation. Cold Front A cold front is the front of a cold air mass. A cold front moves warm air above cooler air. The air is then replaced with colder air. Cold Front Cold fronts move quicker than warm fronts and cause the temperature to fall. Cold fronts tend to bring stormy weather. On a map, we a blue line to represent a cold front. Clouds There are four basic cloud shapes. 1. Cirrus 2. Cumulus 3. Cumulonimbus 4. Stratus Cirrus Clouds Cirrus clouds are the highest clouds. They look like feathers across the sky. They are about 10,000 meters above the Earth. They usually bring fair weather. Cumulus Clouds These clouds look like bright white wads of cotton They form at about 6,000 meters high Cumulus clouds are most often seen with fair weather. Cumulonimbus Clouds These are the largest clouds. They are wide at the bottom, narrow in the middle, and white and flat at the top. They form at about 2,000 meters and can pile up really high! These usually bring heavy rain, high winds, hail, and tornadoes! Cumulonimbus Clouds Stratus Clouds These clouds form gray sheets that spread across the sky. They from low, at about 1,500 meters and can sink all the way to the ground! These clouds often bring heavy mist and snow or drizzle.