module 2 quiz

deposition

(1) The change in state of matter from gas to solid that occurs with cooling. Usually used in meteorology when discussing the formation of ice from water vapor. This process releases latent heat energy to the environment. (2) Laying down of sediment transported by wind, water, or ice.

mass

Any object with mass is influenced by the universal force known as gravity. Newton's Law of Universal Gravitation states: any two objects separated in space are attracted to each other by a force proportional to the product of their masses and inversely proportional to the square of the distance between them.

cyclone

Area of low pressure in the atmosphere that displays circular inward movement of air. In the Northern Hemisphere circulation is counterclockwise, while Southern Hemisphere cyclones have clockwise wind patterns.

mid latitude cyclone

Cyclonic storm that forms primarily in the middle latitudes. Its formation is triggered by the development of troughs in the polar jet stream. These storms also contain warm, cold and occluded fronts. Atmospheric pressure in their center can get as low as 970 millibars. Also called wave cyclones or frontal cyclones.

Newton's second law of motion suggests that the force put on an object equals its mass multiplied by the acceleration produced. The term force in this law refers to the total or net effect of all the forces acting on an object.

Force = Mass x Acceleration or Acceleration = Force/Mass

frictional deceleration

Friction can exert an influence on wind only after the air is in motion. Frictional drag acts in a direction opposite to the path of motion causing the moving air to decelerate (see Newton's first and second laws of motion). Frictional effects are limited to the lower one kilometer above the Earth's surface.

Atmospheric pressure

Generally, these differences occur because of uneven absorption of solar radiation at the Earth's surface (Figure 7n-1). Wind speed tends to be at its greatest during the daytime when the greatest spatial extremes in atmospheric temperature and pressure exist.

aneroid meter

Inside this instrument is a small, flexible metal capsule called an aneroid cell. In the construction of the device, a vacuum is created inside the capsule so that small changes in outside air pressure cause the capsule to expand or contract. The size of the aneroid cell is then calibrated and any change in its volume is transmitted by springs and levers to an indicating arm that points to the corresponding atmospheric pressure.

latent heat

Is the energy required to change a substance to a higher state of matter (solid > liquid > gas). This same energy is released from the substance when the change of state is reversed (gas > liquid > solid).

sublimation

Process where ice changes into water vapor without first becoming liquid. This process requires approximately 680 calories of heat energy for each gram of water converted.

Humidity can be measured using a variety of instruments.

Relative humidity is often determined using a sling psychrometer or a hair hygrometer.

barometer

The first measurement of atmospheric pressure began with a simple experiment performed by Evangelista Torricelli in 1643. In his experiment, Torricelli immersed a tube, sealed at one end, into a container of mercury (see Figure 7d-2 below). Atmospheric pressure then forced the mercury up into the tube to a level that was considerably higher than the mercury in the container. Torricelli determined from this experiment that the pressure of the atmosphere is approximately 30 inches or 76 centimeters (one centimeter of mercury is equal to 13.3 millibars). He also noticed that height of the mercury varied with changes in outside weather conditions.

hydraulic cycle

The hydrologic cycle is a conceptual model that describes the storage and movement of water between the biosphere, atmosphere, lithosphere, and the hydrosphere (see Figure 8b-1). Water on this planet can be stored in any one of the following reservoirs: atmosphere, oceans, lakes, rivers, soils, glaciers, snowfields, and groundwater.

what causes the most evaporated water

The oceans supply most of the evaporated water found in the atmosphere. Of this evaporated water, only 91% of it is returned to the ocean basins by way of precipitation.

melting

The physical process of a solid becoming a liquid. For water, this process requires approximately 80 calories of heat energy for each gram converted.

westerlies

The surface air moving towards the poles from the subtropical high zone is also deflected by Coriolis acceleration producing the Between the latitudes of 30 to 60° North and South, upper air winds blow generally towards the poles. Once again, Coriolis force deflects this wind to cause it to flow west to east forming the polar jet stream at roughly 60° North and South

Beaufort wind scale

This descriptive scale was originally developed by Admiral Beaufort of the British Navy in the first decade of the 17th century. The purpose for this system was to allow mariners to determine wind speed from simple observations. The Beaufort system has undergone several modifications to standardize its measurement scale and to allow for its use on land. Users of this scale look for specific effects of the wind on the environment to determine speed.

ferrel cell

Three-dimensional atmospheric circulation cell located at roughly 30 to 60° North and South of the equator.

Monsoon

are regional scale wind systems that predictably change direction with the passing of the seasons. Like land/sea breezes, these wind systems are created by the temperature contrasts that exist between the surfaces of land and ocean. However, monsoons are different from land/sea breezes both spatially and temporally. Monsoons occur over distances of thousands of kilometers, and their two dominant patterns of wind flow act over an annual time scale.

wind

can be defined simply as air in motion. This motion can be in any direction, but in most cases the horizontal component of wind flow greatly exceeds the flow that occurs vertically. The speed of wind varies from absolute calm to speeds as high as 380 kilometers per hour (Mt. Washington, New Hampshire, April 12, 1934). In 1894, strong winds in Nebraska pushed six fully loaded coal cars over 160 kilometers in just over three hours. Over short periods of time surface winds can be quite variable.

saturation

can be generally defined as the condition where any addition of water vapor to a mass of air leads to the condensation of liquid water or the deposition of ice at a given temperature and pressure.

relative humidity

can be simply defined as the amount of water in the air relative to the saturation amount the air can hold at a given temperature multiplied by 100. Air with a relative humidity of 50% contains a half of the water vapor it could hold at a particular temperature.

what is water cycled through

continually cycled between its various reservoirs. This cycling occurs through the processes of evaporation, condensation, precipitation, deposition, runoff, infiltration, sublimation, transpiration, melting, and groundwater flow.

thermal high

created by the relatively cooler air temperatures and enhanced by the descending air from above. Surface air temperatures are cooler here because of the obstruction of shortwave radiation absorption at the Earth's surface by the cloud. At the surface, the wind blows from the high to the low pressure.

subtropical high pressure zone

does not form a uniform area of high pressure stretching around the world in reality. Instead, the system consists of several localized anticyclonic cells of high pressure. These systems are located roughly at about 20 to 30° of latitude and are labeled with the letter H on Figures 7p-4 and 7p-5. The subtropical high pressure systems develop because of the presence of descending air currents from the Hadley cell. These systems intensify over the ocean during the summer or high Sun season. During this season, the air over the ocean bodies remains relatively cool because of the slower heating of water relative to land surfaces. Over land, intensification takes place in the winter months. At this time, land cools off quickly, relative to ocean, forming large cold continental air masses.

intertropical convergence zone

draws in surface air from the subtropics. When this subtropical air reaches the equator, it rises into the upper atmosphere because of convergence and convection. It attains a maximum vertical altitude of about 14 kilometers (top of the troposphere), and then begins flowing horizontally to the North and South Poles. Coriolis force causes the deflection of this moving air in the upper atmosphere, and by about 30° of latitude the air begins to flow zonally from west to east. This zonal flow is known as the subtropical jet stream. The zonal flow also causes the accumulation of air in the upper atmosphere as it is no longer flowing meridionally. To compensate for this accumulation, some of the air in the upper atmosphere sinks back to the surface creating the subtropical high pressure zone. From this zone, the surface air travels in two directions. A portion of the air moves back toward the equator completing the circulation system known as the Hadley cell.

subpolar lows

form a continuous zone of low pressure in the Southern Hemisphere at a latitude of between 50 and 70° (Figures 7p-4 and 7p-5). The intensity of the subpolar lows varies with season. This zone is most intense during Southern Hemisphere summer (Figure 7p-4). At this time, greater differences in temperature exist between air masses found either side of this zone. North of subpolar low belt, summer heating warms subtropical air masses. South of the zone, the ice covered surface of Antarctica reflects much of the incoming solar radiation back to space. As a consequence, air masses above Antarctica remain cold because very little heating of the ground surface takes place. The meeting of the warm subtropical and cold polar air masses at the subpolar low zone enhances frontal uplift and the formation of inten se low pressure systems.

A wind that blows around curved isobars above the level of friction is called

gradient wind

anemometer

in kilometers per hour (kmph), miles per hour (mph), knots, or meters per second (mps)

pressure

indicated by drawing isolines of pressure, called isobars, at regular 4 millibar intervals (e.g., 996 mb, 1000 mb, 1004 mb, etc.). If the isobars are closely spaced, we can expect the pressure gradient force to be great, and wind speed to be high (see Figure 7n-4). In areas where the isobars are spaced widely apart, the pressure gradient is low and light winds normally exist. High speed winds develop in areas where isobars are closer.

sling psychometer

is a device that consists of two thermometers joined to a piece of plastic or metal (Figure 8c-2). One of the thermometers, called the wet-bulb thermometer, has small cloth hood (wick) that is pulled over the reservoir bulb. The other thermometer has no hood and is called the dry-bulb thermometer. At one end of instrument is a rotating handle. To use the sling psychrometer, the wick is moistened with clean water and the device is twirled in the air using the handle. As the device is spun in the air, evaporation of the water from the wet-bulb thermometer occurs cooling it. The amount of evaporation and cooling taking place is controlled by the dryness of the air. If the air is saturated, the wet-bulb and dry-bulb thermometers would have the same temperature because no evaporation can occur. After a few minutes of twirling, the temperatures of the wet-bulb and dry-bulb thermometers are determined, a value called the wet-bulb depression is calculated (dry-bulb minus wet-bulb temperature), and a psychrometric table is used to find the corresponding relative humidity from the dry-bulb temperature and wet-bulb depression.

mixing ratio

is a measure that refers to the mass of a specific gas component relative to the mass of the remaining gaseous components for a sample of air. When used to measure humidity mixing ratio would measure the mass of water vapor relative to the mass of all of the other gases. In meteorological measurements, mixing ratio is usually expressed in grams of water vapor per kilogram of dry air.

conventional lifting

is associated with surface heating of the air at the ground surface. If enough heating occurs, the mass of air becomes warmer and lighter than the air in the surrounding environment, and just like a hot air balloon it begins to rise, expand, and cool. When sufficient cooling has taken place saturation occurs forming clouds. This process is active in the interior of continents and near the equator forming cumulus clouds and or cumulonimbus clouds (thunderstorms). The rain that is associated with the development of thunderstorm clouds is delivered in large amounts over short periods of time in extremely localized areas.

specific heat

is equivalent to the heat capacity of a unit mass of a substance or the heat needed to raise the temperature of one gram (g) of a substance one degree Celsius. Water requires about 4 to 5 times more heat energy to raise its temperature when compared to an equal mass of most types of solid matter. This explains why water bodies heat more slowly than adjacent land surfaces.

latent heat

is the energy needed to change a substance to a higher state of matter. This same energy is released from the substance when the change of state (or phase) is reversed. The diagram below describes the various exchanges of heat involved with 1 gram of water.

kinetic energy

is the energy of motion, The amount of kinetic energy that a body possesses is dependent on the speed of its motion and its mass. At the atomic scale, the kinetic energy of atoms and molecules is sometimes referred to as heat energy.

el nino

is the name given to the occasional development of warm ocean surface waters along the coast of Ecuador and Peru. When this warming occurs the usual upwelling of cold, nutrient rich deep ocean water is significantly reduced. El Niño normally occurs around Christmas and usually lasts for a few weeks to a few months. Sometimes an extremely warm event can develop that lasts for much longer time periods. In the 1990s, strong El Niños developed in 1991 and lasted until 1995, and from fall 1997 to spring 1998.

pressure gradient force

is the primary force influencing the formation of wind from local to global scales. This force is determined by the spatial pattern of atmospheric pressure at any given moment in time.

centripetal acceleration

is the third force that can act on moving air. It acts only on air that is flowing around centers of circulation. Centripetal acceleration is also another force that can influence the direction of wind. Centripetal acceleration creates a force directed at right angles to the flow of the wind and inwards towards the centers of rotation (e.g., low and high pressure centers). This force produces a circular pattern of flow around centers of high and low pressure. Centripetal acceleration is much more important for circulations smaller than the mid-latitude cyclone.

pressure gradients

may develop on a local to a global scale because of differences in the heating and cooling of the Earth's surface. Heating and cooling cycles that develop daily or annually can create several common local or regional thermal wind systems. The basic circulation system that develops is described in the generic illustrations below

measures of atmospheric humidity

mixing ratio, saturation mixing ratio, and relative humidity.

orographic uplift

occurs when air is forced to rise because of the physical presence of elevated land. As the parcel rises it cools as a result of adiabatic expansion at a rate of approximately 10° Celsius per 1000 meters until saturation. The development of clouds and resulting heavy quantities of precipitation along the west coast of Canada are mainly due to this process.

radiative cooling

occurs when the Sun is no longer supplying the ground and overlying air with energy derived from solar insolation (e.g., night). Instead, the surface of the Earth now begins to lose energy in the form of longwave radiation which causes the ground and air above it to cool. The clouds that result from this type of cooling take the form of surface fog.

force of acceleration

of about 9.8 meters per second per second. As a result of this force, the speed of any object falling towards the surface of the Earth accelerates (1st second - 9.8 meters per second, 2nd second - 19.6 meters per second, 3rd second - 29.4 meters per second, and so on.) until terminal velocity is attained.

gravity causes the density and pressure

of air to decrease exponentially as one moves away from the surface of the Earth

heat

often defined as energy in the process of being transferred from one object to another because of difference in temperature between them. Heat is commonly transferred around our planet by the processes of conduction, convection, advection, and radiation.

saturation ratio

refers to the mass of water vapor that can be held in a kilogram of dry air at saturation.

convergeal or frontal lifting

takes place when two masses of air come together. In most cases, the two air masses have different temperature and moisture characteristics. Oneof the air masses is usually warm and moist, while the other is cold and dry. The leading edge of the latter air mass acts as an inclined wall or front causing the moist warm air to be lifted. Of course the lifting causes the warm moist air mass to cool due to expansion resulting in saturation. This cloud formation mechanism is common at the mid-latitudes where cyclones form along the polar front and near the equator where the trade winds meet at the intertropical convergence zone.

southern oscillation

The formation of an El Niño is linked with the cycling of a Pacific Ocean circulation pattern known as the

gravity shapes these

density and pressure

dew point

the temperature at which water vapor saturates from an air mass into liquid or solid usually forming rain, snow, frost, or dew. Dew point normally occurs when a mass of air has a relative humidity of 100%. This happens in the atmosphere as a result of cooling through a number of different processes.

Direction is measured by an instrument called

wind vane

how temperature relates to kinetic energy

Temperature is defined as the measure of the average speed of atoms and molecules. The higher the temperature, the faster these particles of matter move. At a temperature of -273.15° Celsius (absolute zero) all atomic motion stops.

humidity

describes the fact that the atmosphere can contain water vapor. The amount of humidity found in air varies because of a number of factors.

sensible heat

is heat that we can sense. A thermometer can be used to measure this form of heat. Several different scales of measurement exist for measuring sensible heat. The most common are: Celsius scale, Fahrenheit scale, and the Kelvin scale.

heat capacity

is the amount of heat energy absorbed by a substance associated to its corresponding temperature increase.

thermal low

pressure center created from the heating of the ground surface.

evaporation

Evaporation can be defined as the process by which liquid water is converted into a gaseous state. Evaporation can only occur when water is available. It also requires that the humidity of the atmosphere be less than the evaporating surface (at 100% relative humidity there is no more evaporation). The evaporation process requires large amounts of energy. For example, the evaporation of one gram of water at a temperature of 100° Celsius requires 540 calories of heat energy (600 calories at 0° Celsius).

freezing

The change in state of matter from liquid to solid that occurs with cooling. Usually used in meteorology when discussing the formation of ice from liquid water.

Condensation

The change in state of matter from vapor to liquid that occurs with cooling. Usually used in meteorology when discussing the formation of liquid water from vapor. This process releases latent heat energy to the environment.

coriolois force

which acts upon wind and other objects in motion in very predictable ways. According to Newton's first law of motion, air will remain moving in a straight line unless it is influenced by an unbalancing force. The consequence of Coriolis force opposing pressure gradient acceleration is that the moving air changes direction. Instead of wind blowing directly from high to low pressure, the rotation of the Earth causes wind to be deflected off course. In the Northern Hemisphere, wind is deflected to the right of its path, while in the Southern Hemisphere it is deflected to the left. The magnitude of the Coriolis force varies with the velocity and the latitude of the object (see Figure 7n-6). Coriolis force is absent at the equator, and its strength increases as one approaches either pole. Furthermore, an increase in wind speed also results in a stronger Coriolis force, and thus in greater deflection of the wind. Coriolis force only acts on air when it has been sent into motion by pressure gradient force. Finally, Coriolis force only influences wind direction and never wind speed.

hair hygrometers

work on the fact that hair changes its length when humidity varies. This device usually consists of a number of human or horse hairs connected to a mechanical lever system. When humidity increases the length of the hairs becomes longer. This change in length is then transmitted and magnified by the lever system into a measurement of relative humidity.