RCAC Practice Exam (Meterology) V1

A front is a narrow transition zone between two air masses. Air masses are large bodies of air with similar temperature and humidity characteristics. When two air masses with different characteristics meet, they don't mix easily due to differences in density and temperature. This creates a boundary known as a front, where the two air masses interact. Fronts can bring changes in weather conditions, such as temperature shifts, precipitation, and changes in wind direction. Therefore, the given answer correctly describes a front as a narrow transition zone between two air masses.

The correct answer is 180 degrees at 5 kts. This can be determined by looking at the METAR report, where it states "18005KT". The first three digits (180) represent the wind direction in degrees, while the last two digits (05) represent the wind speed in knots. Therefore, the wind is coming from 180 degrees and has a speed of 5 knots.

The given METAR report states that the visibility is "4SM," which stands for 4 statute miles. This information is indicated after the wind speed and direction (18005KT) and before the weather phenomenon (BR). Therefore, the correct answer is 4 miles.

During the passage of a cold front, warm air is lifted as colder air pushes under it. This occurs because cold air is denser than warm air, causing it to sink and push the warm air upwards. As the cold air replaces the warm air, it creates a lifting mechanism that can lead to the formation of clouds and precipitation. This process is responsible for the development of thunderstorms and other weather phenomena associated with cold fronts.

Relative humidity is a measure of the amount of moisture present in the air compared to the maximum amount of moisture the air could hold at a specific temperature and pressure. It indicates how close the air is to being saturated with water vapor. A higher relative humidity means that the air is holding more moisture, while a lower relative humidity indicates that the air is relatively dry.

Thunderstorms are formed when there is a combination of unstable air, high humidity, and a lifting force. Unstable air refers to air that is rapidly rising due to temperature differences in the atmosphere. High humidity means that there is a significant amount of moisture in the air. A lifting force, such as a front or a mountain, is needed to lift the warm, moist air upwards. These conditions create an environment where the warm air rises and cools, leading to the formation of cumulonimbus clouds and the potential for thunderstorms.

FEW 013 in this weather report means that there are trace to 2/8 of the sky covered in cloud, with the height of the cloud layer at 1,300 feet. This indicates that there are only a few clouds present in the sky, covering a small portion of the sky at a relatively low altitude.

Nimbostratus clouds are typically associated with steady rain. These clouds are characterized by their dark, thick, and uniform appearance, covering the sky and often blocking out the sun. They form at low to middle altitudes and are capable of producing long periods of continuous precipitation. Altostratus and altocumulus clouds may also bring rain, but they are not typically associated with steady rain. Stratocumulus clouds are low-level clouds that may produce light rain or drizzle, but they are not known for steady rain. Therefore, nimbostratus is the most likely cloud type associated with steady rain.

An inversion is a condition when the air temperature aloft is higher than that of the lower atmosphere. This is a phenomenon where warm air is trapped above cooler air, preventing vertical mixing and causing a stable atmospheric condition. Inversions can lead to the formation of fog, smog, and poor air quality as pollutants become trapped near the surface.

A METAR provides a concise and standardized description of the weather conditions observed at a specific station at the time the report is made. It includes information such as temperature, wind speed and direction, visibility, and precipitation. The purpose of a METAR is to provide accurate and up-to-date weather information for aviation purposes, allowing pilots and air traffic controllers to make informed decisions regarding flight operations. Therefore, the correct answer is "observed at a station at the time of the report."

In the northern hemisphere, the winds blow clockwise around a high pressure area and counter-clockwise around a low pressure area. This is due to the Coriolis effect, which is caused by the rotation of the Earth. In high pressure areas, air sinks and moves outward, creating a clockwise flow. In low pressure areas, air rises and moves inward, creating a counter-clockwise flow. This pattern is consistent in the northern hemisphere.

During the day, the diurnal change of surface wind velocity causes it to veer and increase in speed. This is because of the differential heating of the Earth's surface. As the sun rises and the day progresses, the surface temperature increases, leading to the creation of thermal gradients. These thermal gradients cause the wind to veer, or change direction, as air flows from areas of higher pressure to areas of lower pressure. Additionally, the increased temperature difference between the surface and the atmosphere enhances the convective processes, resulting in faster wind speeds.

When flying from an area of low pressure to an area of higher pressure, failure to adjust the altimeter will result in the altimeter indicating too low. This is because the altimeter measures altitude based on atmospheric pressure, and as the aircraft moves into an area of higher pressure, the altimeter will not accurately reflect the change in altitude. As a result, the altimeter will indicate a lower altitude than the actual true altitude of the aircraft.

The correct answer is feet AGL. In Canadian Aerodrome Forecasts (TAF), cloud heights are given in feet above ground level (AGL). This means that the height of the clouds is measured from the ground surface.

The sequence of clouds observed at the airport, starting with cirrus and followed by altostratus and nimbostratus, suggests the passage of a warm front. Warm fronts typically bring in warm air mass, which rises over the cooler air mass ahead of it. This rising warm air creates the cirrus clouds, followed by the altostratus and nimbostratus clouds, which are associated with precipitation. Therefore, the observer should expect the passage of a warm front.

During a descent from 2,000 feet AGL to the surface, the wind typically backs and decreases. "Backing" refers to the change in wind direction in a counterclockwise manner, such as from south to east. As the aircraft descends closer to the surface, it moves into lower levels of the atmosphere where the friction with the ground slows down the wind speed, causing it to decrease.

When air masses are being cooled from below, it can lead to the formation of fog, poor visibility, and layer clouds. As the air cools, the moisture in the air condenses, forming fog and layer clouds. This can reduce visibility, making it difficult to see clearly. The presence of fog and layer clouds is a result of the cooling process and indicates that the air mass is being cooled from below.

Advection fog forms when moist air moves from a warm surface to a colder surface. This occurs because as the warm air comes into contact with the colder surface, it cools down and reaches its dew point, causing the moisture in the air to condense and form fog. The movement of the moist air from a warm surface to a colder surface is the key factor in the formation of advection fog.

When moist warm air rises, it expands due to the decrease in atmospheric pressure. As the air expands, it cools down because the expansion requires energy, which is taken from the air molecules, causing them to slow down and cool. This cooling process leads to the condensation of water vapor, forming clouds. Therefore, the correct answer is that the air cools as a result of expansion as it rises.