METR 121 Test 1

What is standard atmospheric pressure at sea level in a) inches of mercury b)millibars c)hectopascals

. A)29.92 inches Hg. B)1013.25 mb C)1013.25 hPa

In the Northern Hemisphere, why are summers warmer than winters even though the earth is actually closer to the sun in January?

. In the northern hemisphere, summers are warmer than winter despite being further from the sun due to the tilt of the Earth's axis of rotation relative to the solar plane. During the summer, the northern hemisphere is tilted toward the sun such that incoming shortwave radiation falls directly on the Tropic of Cancer.

How is the lower atmosphere warmed from the surface upward?

. The lower atmosphere, or troposphere is warmed from below by incoming shortwave radiation heating up the surface. The air immediately adjacent to the surface is warmed by conduction, leading to convective circulations that carry warm air up above the surface.

Briefly describe how the air temp changes from the earth's surface to the lower thermosphere

3. The temperature decreases with altitude in the troposphere as the layer is heated from below (the surface) by shortwave radiation. The temperature increases with altitude in the stratosphere by the production and destruction of ozone. The temperature decreases with altitude in the mesosphere, the coldest layer of the atmosphere and increases with height in the thermosphere due to ionization by shortwave radiation (think Aurora).

Explain how heat is transferred in our atmosphere by: a)conduction, b)convection or C) radiation

A) Conduction - The trransfer of heat from molecule to molecule (or atom to atom through contact. Always from hot to cold. B) Convection - The transfer of heat by mass movement of a fluid (liquid or gas). The bonds in solids are too strong to permit convective motions. C) Radiation - The transfer of energy by electromagnetic (EM) waves. When electrons are excited in an atom by collisions with neighboring molecules electromagnetic waves are emitted as the excited electrons fall back to their ground state.

List the two primary ways in which fog forms

A) Cooling the air. B) Evaporation and mixing of air masses.

What does the relative humidity represent?

A) Relative humidity measures how close the air is to saturation.

What atmospheric layer contains all of our weather? B) IN what atmospheric layer do we find the highest concentration of ozone? The highest average air temp?

A) Troposphere B) Stratosphere

How does the temp of an object influence the radiation it emits?

According to Wien's law, the peak wavelength of emitted radiation from an object is inversely proportional to its temperature. Hotter objects emit radiation at shorter wavelengths.

Describe the conditions that are necessary for the formation of advection fog

Advection fog forms from moist air moving over a cold surface.

Above what region of the world would you find the ozone hole?

Antarctica.

Why are carbon dioxide and water vapor called selective absorbing greenhouse gases?

Carbon Dioxide and Water Vapor are called selective absorbers since they allow shortwave radiation to pass through the atmosphere without absorption while infrared radiation emitted by the earth and atmosphere are absorbed by these gases and re- emitted both out to space and the Earth's surface.

How can you distinguish altostratus clouds from cirrostratus clouds?

Cirrostratus typically have a halo around them due to the reflection and refraction (bending) of light from the sun or the moon. Cirrostratus are high thin ice clouds that allow a good deal of sunlight to pass through. Altostratus are lower in the atmosphere and composed almost entirely of liquid water. The sun is visible through altostratus, unlike stratus, but appears watery.

Why is cold polar air described as "dry" when the relative humidity is very high?

Cold polar air is dry even though the relative humidity is high because the air has little capacity for containing water vapor. Remember that saturation vapor pressure is only a function of temperature.

How does condensation differ from precipitation?

Condensation is the process of a vapor undergoing a phase change to the liquid state. Precipitation occurs when sufficient condensation has occurred so that the liquid water has sufficient mass so that gravity overcomes all other forces acting to suspend the water droplet.

What are condensation nuclei and why are they important in our atmosphere?

Condensation nuclei are aerosols (e.g. sea salt, dust) that act as a surface for condensation to occur. Remember that spontaneous condensation does not occur at normal atmospheric temperatures and pressures. A surface is needed for condensation to occur. Without these nuclei, haze, fog, clouds, and precipitation would not form.

Clouds with heavy rain showers

Cumulonimbus

Explain how dew, frozen dew, and visible frost form

Dew, frozen dew, and frost all form from surface cooling. Long Wave radiation is the primary mechanism for this cooling. As the surface cools to its dew point, further cooling will lead to condensation, resulting in liquid water formation near the surface and the removal of water vapor from the atmosphere. The removal of water vapor allows the dew point to decrease. Should the temperature fall below the freezing point of water, frozen dew will form. If the dew point is initially below freezing, frost will form.

Explain how incoming energy and outgoing energy regulate the daily variation in temp

During the daylight hours, incoming energy warms the surface and atmosphere. As the Earth heats, the amount of longwave energy emitted increases (Stefan Boltzman law). Once they come into equilibrium, the maximum temperature of the day is reached, typically late in the afternoon. Once the sun sets, only longwave energy is emitted so the surface cools, reaching a minimum around sunrise.

How does evaporation (mixing) fog form?

Evaporation moistens the air, raising the dew point temperature. Mixing of warm moist air with cooler air reduces the overall temperature. If the air temperature cools to the dew point, fog will form.

Even though the actual concentration of oxygen is close to 21% (by volume) in the upper stratosphere, explain why, without proper breathing apparatus, you would not be able to survive there

Even though the concentration of oxygen in the stratosphere is the same as it is in the troposphere (21%) the density of air is so small that you would not be able to breath without a breathing apparatus.

How do the wavelengths of most of the radiation emitted by the sun differ from those emitted by the surface of the earth?

From Wien's law, the Sun emits radiation in the visible portion of the electromagnetic spectrum, termed shortwave radiation, while the Earth emits radiation in the infrared, called longwave radiation.

Explain why the daily range in temp is normally greater in drier regions than in humid regions and on clear days than on cloudy days

Heating of dry soils leads to significant sensible heating, leading to much warmer temperatures. Much of the incoming energy over wet soils goes in to latent heating to evaporate water.

Clouds are most generally classified by height above earth's surface. List the major height categories and the cloud types associated with each

High Clouds: Cirro- Cirrostratus Cirrocumulus Cirrus Middle Clouds: Alto- Altostratus Altocumulus Low Clouds: Strato- Nimbo- Stratus Stratocumulus Nimbostratus Clouds with vertical extent: Cumulo- Cumulus (humilis and congestus) Cumulonimbus

Why do hot and humid summer days usually feel hotter than hot and dry summer days

Hot humid days "feel" hotter than hot dry summer days due to human physiology. When the relative humidity is high, sweat does not evaporate from our bodies. Sweat is a mechanism used to cool our bodies since evaporation is a cooling process. If the air is close to saturation, evaporation is nearly matched by condensation so the cooling effect is nearly matched by heat released by condensation.

Explain why the vegetation on the north-facing side of a hill is frequently different from the vegetation on the south-facing side of the hill

In the northern hemisphere, the south sides of hills are exposed to more daylight than north facing slopes, resulting in less vegetation on the southern facing hills.

Explain why the warmest time of the day is usually in the afternoon, even though the sun's rays are most direct at noon

Incoming shortwave radiation continue to exceed outgoing longwave radiation well into the afternoon.

If it is winter and January in NYC, what is the season and month in Sydney, Australia?

It is still January but it is summer in Sydney.

Why are the largest annual ranges of temps normally observed over continents away from large bodies of water?

Largest temperatures ranges are typically found in the middle of continents well away from large bodies of water due to the much smaller heat capacity of land compared to water. Land heats up and cools down much more rapidly than oceans.

What is latent heat? How is latent heat an important source of atmospheric energy?

Latent heat is the energy absorbed or released to change the phase of a substance. Latent heat is an extremely important component of the atmospheric energy budget as the energy locked up in phase transitions can be carried to far off locations by winds and large scale circulations to be released or absorbed.

Describe each of the controls of temp

Latitude, Land-Sea contrasts, Ocean Currents, and Elevation.

What are the main factors that determine seasonal temp variations?

Latitude, Land-Sea contrasts, Ocean Currents, and Elevation.

What weather conditions are best suited for the formation of a cold night and a strong radiation inversion

Long nights with little wind, dry and cloud free.

Two cities have the same mean annual temp. Explain why this fact does not mean that their temps throughout the year are similar

Mean annual temperature represents the average temperature over a full year. The average temperature in each month could be drastically different. Consider the contrast between San Francisco, CA and Richmond, VA.

Rank the following storms in size from largest to smallest: hurricane, tornado, middle-latitude cyclonic storm, thunderstorm

Mid-latitude cyclone, hurricane, thunderstorm, tornado.

List the four most abundant gases in earth's atmosphere

Nitrogen, Oxygen, Argon, Water Vapor (Carbon Dioxide is small but very important).

Explain how the atmosphere "protects" inhabitants at the earth's surface.

Ozone absorbs ultraviolet radiation.

Describe the conditions that are necessary for the formation of radiation fog

Radiation fog forms from cooling at the surface.

During what part of the day is the relative humidity normally lowest? Normally highest?

Relative humidity is highest before sunrise due to this being the coldest part of the diurnal cycle. When the air temperature is low, the temperature approaches the dew point as the air cannot contain much water vapor. Relative humidity is lowest during the afternoon when the shortwave radiation heats up the surface and convective circulations mix the air, leading to temperatures far exceeding the dew point.

What does saturation vapor pressure primarily depend upon

Saturation vapor pressure depends solely on temperature (exponentially).

What are some of the aerosols in the atmosphere?

Sea Salt, dust, combustion by-products (sulfates), volcanic ash.

How does weather differ from climate?

Short term air temperature, air pressure, humidity, clouds, precipitation, visibility, and wind. It is the Instantaneous state of the atmosphere at a given place and time (e.g., Bowling Green now). Climate is the long term (30 years) patterns and average weather.

When the relative humidity is given why is it also important to know the air temp?

Since saturation vapor pressure depends solely on temperature, in order to know the relative humidity, it is essential to know the air temperature.

Distinguish between temp and heat

Temperature is a measure of the mean internal or thermal energy of a substance. We identify temperature as a measure of hotness or coldness. Heat is the flow or transfer of energy that results from temperature differences.

Explain how radiational cooling at night produces a radiation temp inversion

The Earth is a much more efficient emitter of infrared energy than the atmosphere, so the surface cools more rapidly than the environment leading to the coldest temperatures at the surface, with increasing temperature above.

Explain how the earth and its atmosphere balance incoming energy with outgoing energy

The Earth needs to be energetically balanced with the atmosphere while both the Earth and atmosphere needs to be balanced with the net incoming shortwave radiation in order for the mean temperature of the Earth to stay constant. Of the 100 units of incoming shortwave radiation 30 is reflected back to space, 19 is absorbed by the atmosphere and 51 is absorbed by the surface. The surface also absorbs 96 units (infrared) from the atmosphere. Those 147 units are balanced by the emission of longwave radiation (117 units), evaporation of water (23 units) and convective circulations (7 units). The atmosphere absorbs 111 units of energy from Earth's longwave emissions, 19 units of shorwave radiation, 23 units from latent heating and 7 units from convective circulations. The atmosphere emits 96 units to the surface and 64 units back to space.

Why does the albedo of the earth and its atmosphere average about 30%?

The Earth's atmosphere has a net albedo of 30% due to the refection of incoming shortwave radiation by the surface (4%), from clouds (20%), with the remaining 6% being scattered by atmospheric gases.

How has the earth's atmosphere changed over time?

The Earth's atmosphere was initially composed of hydrogen and helium from the formation of our solar system. Much of the initial atmosphere was lost due to the high internal energy of the early atmosphere and the ease of which light elements could escape Earth's gravitational field. Volcanism released tremendous amounts of water vapor, carbon dioxide, and methane into the atmosphere producing the oceans and life on earth.

How does the Kelvin temp scale differ from the Celsius scale?

The Kelvin scale is an absolute scale that is based on the thermal energy of a substance. 0 refers to absolute zero where the substance has no internal energy (and therefore does not emit radiation. The Celsius scale is based on the freezing point (0) and boiling points (100) of water.

In a volume of air, how does the actual vapor pressure differ from the saturation vapor pressure? When are they the same?

The actual vapor pressure is the pressure exerted by water vapor molecules in the atmosphere (Dalton's law of partial pressure). The saturation vapor pressure is the pressure exerted by vapor molecules when the air can no longer contain additional vapor. This is saturation. When evaporation is exactly matched by condensation.

ON a calm, sunny day why is the air next to the ground normally much warmer than the air several feet above?

The air is very poor thermal conductor so that only the lowest few centimeters of the atmosphere are directly heated by absorbed shortwave radiation.

How does the amount of radiation emitted by the earth differ from that emitted by the sun?

The amount of energy emitted by the Earth is exponentially less that that emitted by the Sun. This is based on the Stefan-Boltzman law which tells us that the total radiant heat energy emitted by an object is proportional to its temperature to the fourth power.

Explain the concept of air pressure in terms of weight of air above some level and why does air pressure always decrease with increasing height above the surface?

The atmosphere is composed of Nitrogen and Oxygen molecules that have mass. Therefore, they are attracted to the Earth by the gravitational force. The weight of the atmosphere is given by the pressure. At any location in the atmosphere, the weight overlying the measurement point gives the atmospheric pressure at that point. The pressure always decreases as one moves up in the atmosphere because the mass of the atmosphere always decreases with altitude. Remember that 50% of the atmosphere is contained in the lowest 5.5 km.

How does the average speed (motion) of air molecules relate to the air temp?

The average speed, or motion, of air molecules measures temperature.

What is the dew point temp? How is the difference b/w dew point and air temp related to the relative humidity?

The dew point temperature is the temperature at which the air needs to be cooled to reach saturation. Dew point depends solely on the amount of moisture in the air. Relative humidity depends both on the amount of water vapor and temperature.

Explain how the earth's atmospheric greenhouse effect works

The greenhouse effect is the result of selective absorbers allowing ]shortwave radiation to pass through the atmosphere while long wave radiation is absorbed and remitted back to Earth, keeping the surface 60 F warmer than it would be in the absence of the greenhouse gases.

What is the ionosphere and where is it located?

The ionosphere is a region of the atmosphere, largely in the thermosphere, atoms become charged (ionized) due to the interaction with high energy shortwave radiation.

What is the primary source of energy for the earth's atmosphere?

The primary source of energy for the Earth's atmosphere is the Sun's radiation.

Explain two ways the relative humidity may be changed

The relative humidity can be changed by altering the air temperature or the water vapor content. While saturation vapor pressure depends solely on temperature, the actual vapor pressure depends on the amount of vapor in the air.

When someone says that "the wind direction today is south," does that mean that the wind is blowing toward the south or from the south

The wind direction specifies the direction the wind is blowing from.

During the Northern Hemisphere's summer, the daylight hours in northern latitudes are longer than in middle latitudes. Explain why far northern latitudes are not warmer than middle latitudes

There are two factors that regulate seasonal temperatures, both the length of daytime hours and the degree to which the sun is above the horizon. Since the sun never gets very high in the sky, despite having continuous daylight, temperatures in the poles do not get very high.

Explain why thermal belts are found along hillsides at night

Thermal belts are found along hillsides as the cold dense air that forms near the surface by radiational cooling drains into the valley under gravity.

ON th basis of temp, list the layers of the atmosphere from lowest to highest

Troposphere, stratosphere, mesosphere, thermosphere.

Of the four most abundant gases in our atmosphere, which one shows the greatest variation from place to place at the earth's surface?

Water Vapor

What are the two most abundant greenhouse gases in the earth's atmosphere?

Water Vapor and Carbon Dioxide.

List four important greenhouse gases in the earth's atmosphere

Water Vapor, Carbon Dioxide, Methane, and Nitrous Oxide.

What are some of the important roles that water vapor plays in our atmosphere?

Water is the most important constituent of the atmosphere when it comes to weather and climate. Think Hydrologic cycle. Not only does vapor condense into liquid water and fall to the earth as precipitation, but its phase changes release tremendous amount of energy (latent heat) that regulate the Earth's energy budget.

Why is the wet-bulb temp a good measure of how cool human skin can become

Wet Bulb is important in meteorology but will not be covered in the exam. It is the temperature that air can be cooled by evaporation. Recall that evaporation is a cooling process so it can serve as a measure of the amount of moisture in the air. The lower the humidity, the greater the amount of moisture that can be e

When a body reaches a radiative equilibrium temp, what is taking place?

When a body reached radiative equilibrium, it absorbs the same amount of radiant energy as it emits.

What greenhouse gases appear to be responsible for the enhancement of the earth's greenhouse effect?

While water vapor is the most abundant greenhouse gas, it is anthropogenic increases in carbon dioxide that is most responsible for global warming.

Explain how the wind generally blows around areas of low and high pressure in the northern hemisphere

Wind blows when there is a horizontal variation of pressure, always from high pressure to low pressure. However, due to the rotation of the earth. The wind is constantly directed to the right in the northern hemisphere, leading to winds blowing clockwise around high pressure regions.

Which clouds are normally associated with a mackerel sky?

cirrocumulus

Clouds with halos?

cirrostratus

clouds with mares' tails?

cirrus

Clouds with anvil top?

cumulonimbus

Clouds with hailstones?

cumulonimbus

Clouds with lightning?

cumulonimbus

Clouds with light continuous rain or snow

nimbostratus

Weather in the middle latitudes tends to move in what general direction

west to east