Convection Currents
•Heat energy transfer between two parts of a fluid of different temperatures •When hot fluids rise and cold fluids sink •Occurs in the atmosphere •Occurs in the oceans •Occurs in planetary mantles •It also occurs in soup Earth’s Mantle •Convection currents flow within the mantle •Causes the tectonic plates to move •Less dense hot magma moves upward •More dense cooler magma moves downward Earth’s Oceans •Convection currents flow within the oceans •Temperature (solar heating) and salinity affects the density of water creating global currents. •More dense water sinks •Less dense water rises Earth’s Atmosphere •Solar radiation heats the Earth’s surface •That heat is transferred to the air by conduction •Air touching the Earth’s surface expands, becomes less dense and rises. •Air cools as it gets higher into the atmosphere. •Cool air becomes more dense and sinks. •Wind is created as the cool air moves in to replace the warm air. High pressure (H) •As air masses cool, they becomes more dense and sinks toward the Earth’s surface. Low pressure (L) •As air masses warm, they becomes less dense and rises above the Earth’s surface Wind •The pressure difference between a high pressure area and its lower pressure surroundings cause a wind to develop •Flows from higher to lower pressure Earth’s atmospheric convection currents cause •Global winds •Local breezes •Cyclones (Hurricane/Typhoon) •Thunderstorms Local Breezes Sea breeze •Gentle wind that flows from the cool air over the water(high pressure) toward the warm air over the land (low pressure). •During the day solar radiation heats the land more quickly than water. Land breeze •Breeze that flows form the cool air above land (high pressure)toward the warmer air above the water (low pressure). •Caused by land cooling more quickly than water in the evening. Valley breeze •During the day, the surface of the mountain heats the air high up in the atmosphere, quicker than the valley floor heats. •This attracts the air from the valley, creating a breeze that blows from the valley floor(high pressure) up towards the top of the mountain (low pressure). Mountain breeze •In the evening, the mountain slopes cool the surrounding air more quickly than the air found lower in the atmosphere. •This causes winds to blow down the mountain (high pressure)towards the valley floor (low pressure). Comments are closed.
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Erik E. Mason
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