How is energy from the sun transferred?
Energy is transferred from the sun to Earth via electromagnetic waves, or radiation. Most of the energy that passes through the upper atmosphere and reaches Earth’s surface is in two forms, visible and infrared light. This transfer of energy can take place by three processes: radiation, conduction, and convection.
What is convection caused by?
Convection occurs when particles with a lot of heat energy in a liquid or gas move and take the place of particles with less heat energy. The liquid or gas in hot areas is less dense than the liquid or gas in cold areas, so it rises into the cold areas. The denser cold liquid or gas falls into the warm areas.
What is the process of convection?
Convection is the process of carrying heat stored in a particle of the fluid into another location. Heat loss may occur by convection to cooler surrounding air or heat gain from surrounding warmer air.
What is the Sun’s role in convection?
The sun’s core is hotter than its outer layers. Hot plasma rises from the core towards the surface, where it cools and sinks back towards the core. This process forms convection cells that we see as solar granules. The lighter color in the granules is the sun’s hot plasma that has risen to the surface.
What are the types of convection?
There are two types of convection: natural convection and forced convection.
What are the applications of convection?
Uses of convection – example
- Car engines are cooled by convection currents in the water pipes.
- Land and sea breezes are caused due to convection currents.
- Rising air over the land are convection currents and are used by glider pilots to keep their gliders in the sky.
What is the simple definition of convection?
1 : the action or process of conveying. 2a : movement in a gas or liquid in which the warmer parts move up and the cooler parts move down convection currents.
What are the characteristics of convection?
Convection is single or multiphase fluid flow that occurs spontaneously due to the combined effects of material property heterogeneity and body forces on a fluid, most commonly density and gravity (see buoyancy).
What is convection flow?
Convective transport (convective flow, bulk flow, convection) may refer to either heat or mass transfer. In the context of membranes, convective flow refers to the transport of fluid (pure solvent or solution) across a porous mem- brane, which is driven by the applied pressure.
What is convection and why is it important?
Convection currents play a role in the circulation of fluids. Convection currents are the result of differential heating. Lighter (less dense), warm material rises while heavier (more dense) cool material sinks. Convection also plays a role in the movement of deep ocean waters and contributes to oceanic currents.
How does natural convection occur?
Natural convection can occur when there are hot and cold regions of either air or water, because both water and air become less dense as they are heated. In nature, convection cells formed from air raising above sunlight-warmed land or water are a major feature of all weather systems.
What is convection energy transfer?
When a fluid, such as air or a liquid, is heated and then travels away from the source, it carries the thermal energy along. This type of heat transfer is called convection. The fluid above a hot surface expands, becomes less dense, and rises.
What are the similarities between conduction convection and radiation?
All Answers (3) Heat may be transferred from one place to another by 3 methods: conduction in solids, convection of fluids (liquids or gases), and radiation through anything that will allow radiation to pass. Both conduction & radiation involve heat transfer “which is similarity” .
What are the 3 methods of energy transfer?
Heat can be transferred in three ways: by conduction, by convection, and by radiation. Conduction is the transfer of energy from one molecule to another by direct contact.
How do you calculate heat transfer in convection?
Common units used to measure the convective heat transfer coefficient are:
- 1 W/(m2 K) = 0.85984 kcal/(h m2 ° C) = 0.1761 Btu/(ft2 h ° F)
- 1 kcal/(h m2 ° C) = 1.163 W/(m2 K) = 0
What factors affect convection heat transfer?
spontaneous convection
- exposed surface area.
- viscosity.
- density.
- conductivity (when conductivity is high, there is no need for convection)
- acceleration due to gravity.
What is the relation between convection heat transfer coefficient?
Mechanism of Forced Convection The fluid motion enhances heat transfer (the higher the velocity the higher the heat transfer rate). The convective heat transfer coefficient h strongly depends on the fluid properties and roughness of the solid surface, and the type of the fluid flow (laminar or turbulent).
What is the purpose of forced convection?
Forced convection creates a more uniform and therefore comfortable temperature throughout the entire home. This reduces cold spots in the house, reducing the need to crank the thermostat to a higher temperature, or putting on sweaters.
Is wind forced convection?
The convection caused by winds is natural convection for the earth, but it is forced convection for bodies subjected to the winds since for the body it makes no difference whether the air motion is caused by a fan or by the winds.
Where is forced convection used?
Forced convection is often encountered by engineers designing or analyzing heat exchangers, pipe flow, and flow over a plate at a different temperature than the stream (the case of a shuttle wing during re-entry, for example).