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Sharpen Your General Knowledge
Shamim Ansary:
How Hot Is Lava and How Viscous Is It?
Exit temperatures—the temperature of lava as it comes from the mouth, or crater, of volcanoes—indicate that lava’s heat varies.
The temperature ranges from 700 to 1,200° Celsius (1,300 to 2,200° Fahrenheit). At its hottest, lava is about 10 times the temperature of boiling water.
It also ranges in viscosity, or how thick or runny it is. Lava can be very thin and fluid, or it can be so thick that it almost doesn’t flow.
The estimated daily lava production of Mauna Loa plus Kiluaea, 2 large volcanoes in Hawaii, would fill 65,000 cement trucks.
Shamim Ansary:
How Does Ultraviolet Radiation Cause Skin Cancer?
The prevailing theory involves damage to the DNA of skin cells.
It is the shorter UVB rays, which penetrate only the top layers of the skin, that are suspect, while the longer and more deeply penetrating UVA rays cause wrinkles and aging.
In tissue cultures, UV damages the DNA of cells, but humans have an enzyme that repairs it. Due to a genetic defect, some people lack the repair enzyme.
The hypothesis is that in the body such DNA damage occurs all the time and is constantly repaired, but some cells do not get repaired, or get repaired improperly, and this is how skin cancer begins.
Researchers found a specific kind of DNA damage in a gene called CQ that occurs in this way. In the error, two DNA units of the type designated as thymine are side by side, instead of two units of the cytosine type.
The error is called a thymine dimer. It is presumed that the brakes on cell multiplication come off because of it, leading to uncontrolled proliferation of cells into a tumor.
Ultraviolet radiation is implicated in the vast majority of nonmelanoma skin cancers, like basal cell carcinoma and squamous cell carcinoma. It is also linked to melanoma, though less clearly.
Shamim Ansary:
What Is Ozone and How Does It Protect the Earth From Ultraviolet Radiation?
Ozone is a unique form of oxygen, and it lies several miles (kilometers) above Earth in the atmosphere.
It serves as a filter against the Sun’s powerful and dangerous ultraviolet rays.
Without this layer of atmospheric protection, ultraviolet radiation would cause many health problems, from skin irritation to cancer in humans, not to mention the harmful effects on other living creatures.
Shamim Ansary:
What Are the Different Kinds of Lava and What Are They Called?
The two most prevalent types of lava worldwide, pahoehoe (pronounced pa-hoy-hoy) and aa (pronounced ah-ah), take their names from the native Hawaiian language.
The state of Hawaii is actually a chain of volcanic islands, where pahoehoe and aa are both found in abundance.
Pahoehoe has the shape of thick cords of rope or puffy billows. It can look something like black whipped cream. When highly fluid lava flows, the outer surface area congeals to form a thin, flexible exterior.
The lava inside continues to run, molding the outside layer into ropelike forms. These shapes remain when the entire mass solidifies.
Aa results from oozing semisolid lava. As aa flows, it carries rough, jagged shards of rock along its path. Aa hardens into sharp, splintery, knifelike edges.
You can walk comfortably on cold pahoehoe barefoot, but aa will slice the soles of your shoes.
Shamim Ansary:
How Do Rivers and Lakes Exist Underground?
Rivers run underground for the same reasons, and as a result of the same causes, as rivers on the surface.
Earth’s crust soaks up precipitation until it can hold no more. Some areas of the crust are so absorbent that water gathers deep underground.
If the crust’s material is more easily eroded underground, the water will begin to flow under the surface. It may emerge onto the surface at a later point in its course if the terrain changes. In the same way, a surface river can disappear underground if the rock material is more easily eroded there.
Similarly, underground lakes have the same characteristics as surface lakes. Whether water gathers above ground or underground depends on the ability of the surrounding environment to absorb water.
Precipitation falling on saturated ground might erode the softer earth underground until it reaches a resilient layer instead of pooling on the surface.
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