Survey
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
* Your assessment is very important for improving the workof artificial intelligence, which forms the content of this project
WEATHER AND CLIMATE How do they differ? • Weather - short term - at a given place and time in the troposphere – Temperature, pressure, humidity, precipitation, sunshine, cloud cover, wind direction & speed. • Climate - long term average – General pattern of atmospheric conditions – Main factors are temperature and precipitation Why does weather change? • Caused by masses of air - either warm or cold that are either high or low pressure and move across the land • Changes as air masses replace or meet one another. • FRONT - where air masses meet. Warm front • Boundary between approaching warm air mass and cool air mass it is replacing. • Warm air less dense & rises over cool air – Moisture – Thick clouds – Rainfall common Cold front • Cold air meeting warm air • More dense so wedges under warm air – Thunderheads – Precipitation – Surface winds and thunder storms • Afterwards, cool temp. & clear skies Properties of warm and cold air • Warm air rises, cold air sinks • As air rises,cools, releases water at the equator - radiates heat into space - low pressure at equator • Cooler drier air - more dense, sinks - creates high pressure areas • Heats again, rises, etc • Causes different climate patterns and vegetation. Pressure • High pressure air mass - cool, dense air descends toward earth’s surface and becomes warmer. Fair weather follows for as long as mass remains. • Low pressure air mass - cloudy, sometimes stormy weather - Less dense warm air spirals inward toward center, rises, cools, moisture condenses and rains. Microclimates • Topographic features create local climatic conditions - differ from the general climate of the region. • Mountains - interrupt wind patterns and storm movements • Moisture is dropped on the windward side of mountains and on the leeward side is the RAINSHADOW EFFECT. • Arid or semiarid conditions Causes of Microclimates • Topography can cause different location to receive different amounts of sunlight. • Vegetation also creates microclimates forests are warmer in winter, cooler in summer, have lower wind speeds and higher humidity. • Cities create microclimates- buildings, asphalt, hold heat, change wind patterns, etc. Rainshadow effect Hadley Cells Global Circulation of air and regional climates • Several factors affect regional climates: – Uneven heating of earth’s surface • Air is heated much more at equator than at poles- sun’s rays hit at an angle due to tilt – Seasonal changes in temperature and precipitation – Earth’s rotation on its axis • Causes coriolis effect winds are deflected to the right in the northern hemisphere and to the left in the southern hemisphere • Results in 6 convection cells called Hadley cells - move heat & water .