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Simple Answer:
Warm air rises during convection. Perhaps better said, natural convection of air is the rising of less-dense warm air relative to the more-dense cold air.
This is a simple matter of buoyancy. Gravity pulls everything downward, but the pull is proportional to mass and items immersed in a fluid that have lower mass per unit volume than the fluid will tend to float, i.e. experience a buoyant force up as gravity pulls harder downward on the surrounding fluid.
Causes and Explanation:
Everyone says "Warm air rises" and that is an example of natural convection. Convection requires a fluid, heat source and gravity. The heat source causes a temperature gradient in the fluid so that buoyancy of the warmer fluid causes it to rise.
Buoyancy is the reasons bubbles rise and hot air balloons float and anything light, like a piece of wood, raises to the surface. The gravitational force experienced by a volume of material is just its weight, i.e. mass times gravity. Mass is the density of the material times its volume. So, if the object (like wood) has a lower density than water, the force of gravity on the object is less than the equivalent volume of water. The buoyant (upward) force is the difference in the wight of the object and the weight of the same volume of liquid.
Light objects experience the upward buoyant force and if the fluid (air or water or any fluid) is heated and expands, then it has a larger volume and less density and it also experiences the upward force.
The natural buoyancy of warmer fluids causes the force that moves the fluid and that movement is what we call natural convection.
Other Aspects:
- Convection is why we say "heat rises." And, an interesting side observation is that when water cools near the freezing point, it actually gets lighter as the temperature drops from 4 C to 0 C, hence causing the cooler water in that range to be less dense and more buoyant.
- There is also something called forced convection where fluid is moved by artificial means such as air pushed by a fan. Most home heating occurs with "forced convection" but years ago natural convection resulting from buoyancy of hat air was the cause for air circulation.
- Convection is a main driver of our weather, but locally and globally. Surface air warmed when the sun sticks the Earth and is changed to heat which gets absorbed by the air. Surface air tends to rise and takes surface moisture with it. If there is enough of the moisture, it comes back as rain somewhere else. Globally, the oceans give up most of the moisture we later experience as rain and the warmest area of the planet, near the equator, produces large scale convection of air that is essential to global weather patterns.
A convection current rises due to the principle of buoyancy. When a fluid is heated, it becomes less dense and therefore rises above the cooler, denser fluid around it, creating a circular flow. This rising motion is driven by the combination of thermal expansion and the force of gravity.
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Heat from the earth's interior causes convection currents in which layer of earth?
Convection currents in the magma drive plate tectonics.Heat generated from the radioactive decay of elements deep in the interior of the Earth creates magma (molten rock) in the aesthenosphere.
Why do convection currents sink back to the core?
Convection currents sink back to the core in the Earth's mantle because as the material in the mantle cools, it becomes denser and sinks due to gravity. This sinking motion completes the cycle of convection, where warmer material rises and cooler material sinks, driving the movement of tectonic plates.
What caused the zombie Apocalypse in The Walking Dead?
It is never stated what actually causes the zombies to rise up. That is part of what makes the series so frightening - the thought that something like this could just start happening for no reason.
Why a dog lays next to a wooden stove convection?
they come in indirect contact
Upward force on a bird's wing?
It is called Lift. The difference in pressure above and below the wigs as a bird moves through the air produces an upward force that causes the bird to rise.
An increase in wind causes this current to increase What type of current is it?
Convection is the process that causes warm air to rise and cold air to sink. As such, the winds caused by this process are called convection currents.
How a convection current formed in the beaker?
A convection current in a beaker is formed when the temperature gradient causes fluid to heat up, become less dense, and rise. As the fluid rises, it cools down, becomes denser, and falls back down to be heated up again. This continuous cycle of rising and falling creates the convection current in the beaker.
Valley breeze in a sentene?
Convection causes it to rise, causing a valley breeze
What is a current when solids gases or liquids rise and sink in a looping path?
Convection
How is a space heater an example of convection?
A space heater is an example of convection because it warms up the air around it. The heater emits heat which causes the air molecules to become less dense and rise, creating a convection current that circulates the warm air throughout the room.
What make fluids rise and sink in a convection current?
Fluids rise and sink in a convection current due to differences in temperature and density. When a fluid is heated, it becomes less dense and rises, creating an upward flow. As it cools, it becomes more dense and sinks, creating a downward flow. This continuous cycle of heating and cooling drives the convection current.
Which process causes the hot air to rise?
The process that causes hot air to rise is called convection. As air is heated, it becomes less dense and more buoyant, causing it to rise. This creates vertical air currents that continuously cycle warm air upwards.
When can convection occur in a substance?
Convection can occur in a substance when there is a temperature gradient present, meaning that one part of the substance is hotter than another. This temperature difference causes the warmer, less dense portion of the substance to rise and the cooler, denser portion to sink, creating a convection current.
How is gravity used in the procss of convection?
Gravity causes the less dense stuff to rise
Why is a hot air ballon examples of convection?
A hot air balloon is an example of convection because the process of heating the air inside the balloon causes it to become less dense and rise. This creates a convection current where the hot air rises and the cooler air around it sinks, allowing the balloon to float.
Where is a mantle convection current most likely to move upward?
A mantle convection current is most likely to move upward at divergent plate boundaries such as mid-ocean ridges. Here, the heat from the Earth's interior causes the mantle material to rise, creating new crust as it cools and solidifies.
What causes magma to rise to earths surface?
The magma is in the mantle, the layer under the crust. There is a convection current caused by radioactivity in the inner core which causes the plates to move. Therefore the constructive plates move apart which means magma can rise up. It'll then solidify and this is what makes volcanoes. Hence CONSTRUCTive.
