Question 1

City A has an air pressure of 1,000 millibars. City B has an air pressure of 1004 millibars. The distance between the two cities is 100 kilometers. The difference of 4 millibars over 100 kilometers is known as ________.

Accepted Answer

The difference in air pressure over a certain distance is known as the pressure gradient. Therefore, the correct answer is C. Wind, force, velocity, and Coriolis effect are other atmospheric factors, but they are not relevant to this specific question.

Question 2

Wind speed may be roughly indicated by ________.

Accepted Answer

The spacing of isobars on a weather map can indicate wind speed, as the closer the isobars are together, the stronger the pressure gradient force, which results in stronger winds.

Question 3

Which factor is corrected for on most maps of atmospheric pressure?

Accepted Answer

Most maps of atmospheric pressure correct for altitude, as atmospheric pressure decreases with increasing altitude due to the reduction in air density.

Question 4

The pressure of a gas is proportional to its temperature and ________.

Accepted Answer

According to the Ideal Gas Law, PV = nRT, where P is pressure, V is volume, n is the number of moles of gas, R is the ideal gas constant, and T is the absolute temperature. By rearranging this equation, we get P/T = nR/V. Therefore, the pressure of a gas is inversely proportional to its volume, and directly proportional to the number of moles of gas and the absolute temperature. Density is directly proportional to the number of moles of gas and inversely proportional to the volume, so it is also directly proportional to pressure and temperature. Therefore, the pressure of a gas is proportional to its temperature and density, making choice C the correct answer.

Question 5

An Earth surface pressure of pressure of 1,005 millibars is associated with ________.

Accepted Answer

An Earth surface pressure of 1,005 millibars can be associated with either lows or highs depending on the surrounding atmospheric conditions and pressure gradients.

Question 6

The pressure of a gas is proportional to its density and ________.

Accepted Answer

The pressure of a gas is determined by its temperature and density, according to the ideal gas law: PV = nRT. Therefore, if the density of the gas increases, the temperature or pressure must also increase to maintain the same amount of gas. Chemical composition, altitude, adiabatic rate, and friction do not directly affect the pressure of a gas.

Question 7

The rate of pressure decrease ________.

Accepted Answer

As altitude increases, the air pressure decreases. This is due to the decrease in density of the air molecules at higher altitudes. However, the rate of pressure decrease is not constant but rather decreases with altitude. This is because the higher in altitude an object is, the less pressure there is pushing down on it from the weight of the air above it.

Question 8

At Earth's surface, warm temperatures are associated with ________.

Accepted Answer

Warm temperatures at Earth's surface are typically associated with low pressure because warm air rises, leading to a decrease in pressure at the surface.

Question 9

The angle of the wind flow across the isobars ________.

Accepted Answer

According to the Buys-Ballot's law, the angle between the wind and the isobars decreases with height in the Northern Hemisphere and increases with height in the Southern Hemisphere. This means that the wind flow across the isobars becomes smaller with height.

Question 10

________ are map lines connecting points of equal atmospheric pressure.

Accepted Answer

Isobars are lines connecting points of equal atmospheric pressure, typically measured in millibars (mb). Contours are lines connecting points of equal terrain elevation, isohyets are lines connecting points of equal precipitation, and isotherms are lines connecting points of equal temperature.

Question 11

When air is heated it expands and ________.

Accepted Answer

When air is heated, it expands and its density decreases, causing the pressure to lower. This is a fundamental principle in thermodynamics, where the increase in temperature leads to an increase in volume and a decrease in pressure for a given mass of air in a closed system.

Question 12

At sea level, the atmosphere exerts a force closest to ________ kilogram(s) per square centimeter.

Accepted Answer

The force exerted by the atmosphere at sea level is known as standard atmospheric pressure, which is equal to 1 atmosphere (atm) or 101,325 Pascal (Pa). In terms of kilogram-force per square centimeter (kgf/cm2), this is approximately 1.03 kgf/cm2, which is closest to 1 kgf/cm2. Therefore, the answer is A) 1.

Question 13

A(n) ________ is a linear zone of lower pressure between two areas of high pressure.

Accepted Answer

A trough is a linear zone of lower pressure between two areas of high pressure.

Question 14

The denser packing of molecules at the bottom of the atmosphere than molecules at the top of the atmosphere is a result of ________.

Accepted Answer

Gravity is responsible for the denser packing of molecules at the bottom of the atmosphere. As molecules are attracted to Earth's surface by gravity, the ones closest to the surface are held more tightly and compressed by the weight of the ones above them, resulting in greater air density at lower altitudes.

Question 15

Of the weather elements below, which is the one of which we are usually LEAST aware without the use of weather instruments?

Accepted Answer

While we may feel the effects of pressure changes (such as headaches or ears popping), we are often not aware of the actual pressure without the use of instruments. Temperature, wind, and moisture can all be felt or observed without the use of instruments.

Question 16

Gas molecules in the lower atmosphere ________.

Accepted Answer

Gas molecules in the lower atmosphere are readily compressed and heated. This is because they are not strongly bound to each other and have high kinetic energy, which allows them to move around and collide frequently.

Question 17

Flowing air responding to the difference between higher and lower pressure is responding to the ________.

Accepted Answer

Flowing air responds to differences in pressure, and the force that moves air from higher to lower pressure is called the pressure gradient.

Question 18

A "dynamic low" is produced by ________.

Accepted Answer

A "dynamic low" is produced by the strong rise of air, which is typically associated with areas of low pressure.

Question 19

The basic unit of pressure mapped on weather maps is ________.

Accepted Answer

Millibars (mb) are the basic unit of pressure commonly used on weather maps.

Question 20

The density of a substance might be measured in ________.

Accepted Answer

Density is defined as mass per unit volume, therefore the most appropriate unit of measurement is kilograms per cubic meter (kg/m³). Choices A, C, and E are not appropriate units for measuring density, while choice B refers only to volume and does not include mass.

Quiz 5: Atmospheric Pressure and Wind