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Weather. What is Weather. The state of the atmosphere often described as measured values of wind speed, temperature, air pressure, precipitation, and humidity. What Drives Weather Conditions. Energy from the sun drives Earth’s weather and climate
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What is Weather • The state of the atmosphere often described as measured values of wind speed, temperature, air pressure, precipitation, and humidity
What Drives Weather Conditions • Energy from the sun drives Earth’s weather and climate • IR radiation from the sun heat’s up the atmosphere
Convection Currents in Earth’s Atmosphere • As temperature of the air molecules increase, air rises • As the air rises it cools down and the air starts to fall back to the surface http://www.youtube.com/watch?v=D52rTzibFRc
How Does Air Pressure Affect Weather • Review as altitude decreases air pressure increases • When air pressure changes, weather changes • Air pressure increases = clear skies, more sun, less wind, drier weather ahead • Air pressure decreases = clouds, less sun, more wind, and possibly precipitation of some kind
How Wind Affects Weather • As an air mass gains heat, molecules move faster creating an air mass with low pressure • As an air mass cools, the particles slow down creating an air mass with high pressure • Difference in air mass causes winds to blow from regions of higher pressure to regions of lower pressure • The greater the pressure difference, the faster the wind blows
Fronts • A boundary between two air masses of different density, moisture, or temperature.
Cold Front • Defined as the leading edge of a cooler mass of air, replacing (at ground level) a warmer mass of air.
Warm Front • Defined as the leading edge of an advancing mass of warm air; it separates warm air from the colder air ahead http://youtu.be/huKYKykjcm0