Use the following experiment to answer questions #16-#20. The materials needed are an ice cube tray, water, a clear jar or glass, and food coloring (darker food colorings are better). 16) Mix the water and food coloring and pour it into the ice cube tray. Put the ice cube tray in the freezer till frozen. Once frozen, fill the clear glass with warm water. Add one colored ice cube to the glass. Observe what happens. What starts to happen?

17) Does the colored water sink or float?

18) Why does the colored water behave in this manner?

19) How does this experiment show heat transfer?

20) What is this process called?

the water begins to sink to the bottom of the glass.  The colored water behaves this way because of convection currents. As the warm air rises, a pattern of air movement is formed called a convection current. We can see this in air and in water.  The process is convection current.

Explanation:

Convection is one of three main types of heat transfer. The other two being radiation and conduction. Convection is the transfer of heat by the movement of heated particles into an area of cooler particles. You can experience convection when you light a match. The air directly above the lit match is always hotter than the air around the match.

This difference in temperature around the match is caused by effect of heat on the density of air. Hot air is less dense than cool air and will rise leaving the cooler air below. As the warm air rises, a pattern of air movement is formed called a convection current. We can see these convection currents in air and in water.

Convection currents in the atmosphere affect our weather. The rising of warm air and falling of dense cool air causes our winds. When warm, moist air rises and mixes with cold air, the atmosphere becomes unstable. This causes thunderstorms.

The Gulf Stream off the eastern coast of the States is a convection current. It carries warm water from the tropics up the east coast north toward the cold arctic waters.

 Heat affects the density of water as well. You can create your own convection current with water that will allow you to see the currents caused by the density difference of water at different temperatures.

The warm water will melt the ice cube, but the resulting water will be very cold. This cold, dense water will sink to the bottom of the glass. You can see this happening because the melted water from the ice cube will be whatever color you made your ice cube.

As the water warms, it will rise back to the top of the glass. The colored water will allow you to see the convection current in the glass.

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step 1: nitrogen fixation- conversion of atmospheric no₂ into forms useful to plants by lightning, bacteria, and cyanobacteria.

step 2: nitrification-process of converting ammonia to nitrite or nitrate.

step 3: assimilation-plant roots absorb new form of nitrogen.

step 4: ammonification-conversion of organic nitrogen to ammonia by bacteria involved in decomposition.

step 5: denitrification-bacteria turns the decomposed matter back into n₂o, which is released into atmosphere; repeat cycle.