Category Archives: Phenomena
On the morning of August 3, 1492, Christopher Columbus set sail on his first voyage to the Americas. He sailed south along the west coast of Africa, searching for the easterly “trade winds,” discovered earlier by the Portuguese, that would propel his fleet westward toward what he thought was India.
The trade winds are a component of a global-scale tropical circulation feature known as the Hadley cell. This cell is driven by the fact that the equator is heated more intensely than latitudes to its north and south, resulting in the production of collections of thunderstorms girdling the globe roughly along the equator. Continue reading
Fires require something to burn plus air to supply oxygen and a heat source to get the fuel to its ignition temperature.
Once a fire starts, weather is one factor of how it will spread and if it will grow. The important weather factors are temperature, wind and humidity. Warmer temperatures allow fuels to ignite quickly, and low humidity keeps the fuel dry and easy to burn. Wind brings oxygen to the fire and also can help to spread it. Continue reading
Ozone (O3) is a molecule formed by three oxygen atoms.
Ozone that resides in the stratosphere absorbs ultraviolet rays of the sun, protecting life on Earth’s surface from these high-energy electromagnetic waves. O3 also can occur near the ground, where it is considered a pollutant, as it is a chemically reactive gas that can cause respiratory problems when breathed. Continue reading
Light is a form of electromagnetic energy that does not need matter to propagate. We can characterize this energy by its wavelength, which is the distance along a wave from one crest to another. Our eyes are sensitive to light with wavelengths between approximately 0.4 to 0.7 microns. Blue colors have shorter wavelengths, while red colors have longer ones.
When light interacts with particles suspended in air, it can be scattered or absorbed. Energy that is scattered causes a change in direction of the light path. The amount of light that is being scattered is a function of the size of the particle relative to the wavelength of the light falling on the particle. While all colors are scattered by air molecules, violet and blue are scattered most. The sky looks blue, not violet, because our eyes are more sensitive to blue light. Continue reading
Picture a rock thrown into a lake on a calm day. That is an excellent example of what a gravity wave looks like.
Ripples migrate from where the rock hits the water, causing an up and down motion along the water’s surface. As we get farther away from the point where the rock hit the water, the waves dampen, becoming less defined. Continue reading