Meteorology

What is meteorology the study of?

Physics and chemistry of Earth’s atmosphere

Which of the following is not what meteorology studies?

Meteors flying through outer space

What is the main goal of meteorologists?

To unserstand how Earth’s atmosphere works

Which of the following is an application of meteorolgy?

All of the above

Where might meteorologists work?

All of the above

Which subject might a meteorology degree require?

All of the above

What is the main focus of this course?

Weather analysis and forecasting

What does the skin of an apple represent in the comparison with Earth?

Earth’s atmosphere

Approximately what percentage of Earth’s radius is represented by 50 km of atmospheric thickness?

8%

Which statement about the upper boundary of Earth’s atmosphere is accurate?

It has no definite upper boundary

Which gas accounts for approximately .93% of dry air?

Argon

What is the approximate concentration range of water vapor listed in the passage?

0-4%

Approximately how many carbon dioxide molecules are present per million atmospheric molecules?

A little over 400 molecules per million

Which gas listed in the table has the smallest stated concentation?

Nitrous oxide

What is the universal time standard used by meteorologist?

Greenwich Mean Time (GMT)

What is the Prime Meridian?

The line at 0 degrees longitude

Which three terms refer to the same universal time standard in the lesson?

GMT, UTC, and Z-time

Why do meteorologists use a universal time standard?

To synchronize weather observations around the world

On a 24-hour clock, what time is 1500 hours?

3:00 PM

If it is 1500 UTC, what time is it in the Eastern United States during Eastern Standard Time (UTC-5)?

10:00 AM

Chicago is in Central Standard Time (UTC-6). If it is 9:00 in CHicago, what time is it in UTC?

3:00 PM UTC

Approximately how many degrees of longitude does each time zone span?

15 degrees

When is Daylight Saving Time generally observed in the United States, according to the notes?

From the second Sunday in March to the first Sunday in November

What happens when you travel westward across the International Date LIne?

The calendar advances one day

What is a station model?

A graphical display of current weather conditions at a weather station

What does air temperature measure scientifically?

The average kinetic energy of air molecules

Where is temperature located on a station model?

Upper left corner

What is the dew point?

The temperature to which air’s water vapour must be cooled for condensation to occur

Where is dew point located on a station model?

Lower left corner

What does a higher dew point generally indicate?

More water vapour in the air

At what dew point does air generally begin to feel muggy or sticky for most people

60 F

Why is horizontal visability important to meteorologists?

It affects transportation safety, including driving and aircraft landings

In the US, what unit is typically used to report visibility on a station model?

Miles

When is a non-precipitating obstruction, such as fog, generally reported on a station model?

When visibility drops to seven miles or fewer

What does sky coverage describe

The portion of the sky covered by clouds

How many sections is the sky-coverage pie chart divided?

8 seconds

Which official sky-cover category represents cloud coverage of 3/8 to 4/8?

Scattered

What does an X in the sky-cover circle on a station model indicate?

Sky obscured

Wind direction is reported based on which direction?

The direction from which the wind blows

A wind blowing from the southeast is represented by which compass angle?

150 degrees

What unit is always used to express wind speed on station models?

Knots

A station model shows one long wind barb and one short wind barb. What is the total wind speed?

15 knots

What wind speed does a triangular wind barb represent?

50 knots

What does a larger circle drawn around the sky-coverage circle indicate on a station model?

Calm surface winds

What does a 40% chance of precipitation mean?

There is a 40% chance that any point in the forecast area will receive at least .01 inches of rain

What does probability of precipitation not tell you?

How long it will rain or how heavy the rain will be

What is climatology?

A long-term averages and extremes of weather at a location

How are normal temperatures calculated by meteorologists?

By averaging temperatures over a 30-year period

How often does the averaging period for calculating new nromal tmerpatures change?

10 years

What is the temperature range?

A difference between the maximum and minimum temperatures

Why do flat maps of Earth always have some distortion?

Earth is spherical, and its surface cannot be flattened without distortion

What is a map projection?

A technique used to represent Earth's curved surface on a flat map.

From which perspective is a polar stereographic projection viewed?

From above the North or South Pole.

How do latitude lines appear on polar stereographic projections?

As large circles or arcs.

How do longitude lines appear on polar stereographic projections?

As straight lines that converge at the poles.

When determining wind direction on a polar stereographic map, what should you use to orient yourself?

The local latitude arcs and longitude lines.

What information does a topographical map show?

Elevation and changes in land height

What is an isopleth?

A line connecting points of equal value

What does having more contour lines on a topographical map generally indicate?

Greater change in elevation

Why do meteorologists use contour maps?

To identify patterns in weather data more easily

If point P is located halfway between the 3,000 ft and 4,000 ft countour lines, what is its estimated elevation?

3,500 ft

What is interpolation when interpreting contour maps?

Estimating a value between two known contour lines

What are isotherms?

Contour lines connecting points of equal temperature

What are isobars?

Contour lines connecting points of equal air pressure

What types of weather is generally associated with surface high-pressure and low-pressure systems?

High pressure brings fair weather, while low pressure often brings cloudy and rainy weather

What is a gradient in meteorology?

The change in a weather variable over a certain distance

What do tightly packed contour lines indicate on a topographical map?

A large elevation gradient and steep terrain

What do tightly packed isobars indicate on a weather map?

A large pressure gradient and potentially strong winds

What do tightly packed isotherms represent on a temperature map?

A large temperature change over a short distance

Why do meteorologists pay close attention to large temperature and pressure gradients?

They can identiry areas where active or interesting weather may oocur

What is the scientific definition of radiation?

The emission and transfer of energy through a medium via particles or waves

What causes electromagnetic radiation to be produced?

Oscillating or vibrating charged particles, such as electrons

What happens to the wavelength decreases?

The wavelength decreases

Which type of electromagnetic radiation has the longest wavelengths?

Radio waves

Which types of electromagnetic radiation are most commonly used by meteorologists to observe the atmosphere?

Microwaves, infrared, and visible light

According to Planck’s Law, which statement best describes how objects emit electromagnetic radiation?

Every object emits radiation at all wavelengths at all times

According to Wien’s Law, what happens to the wavelength of peak emission as an object’s temperature increases?

The peak wavelength becomes shorter

What does the Stefan-Boltzmann Law describe?

The relationship between temperature and total energy emitted per unit area

According to Kirchhoff’s Law, what can be said about an object at constant temperature?

An object that absorbs radiation efficiently at a wavelength also emits efficiently at that wavelength

Why does the Sun’s peak emission occur in the visible portion of the electromagnetic spectrum, while Earth’s peak emission occurs in the infrared?

The sun is much hotter than Earth

What are the three possible outcomes when electromagnetic radiation encounters a medium?

Absorption, scattering, and transmission

What happens during transmission of electromagnetic radiation?

Radiation passes through a medium unaffected

Which atmospheric gas absorbs much of the Sun’s incoming ultraviolet radiation in the stratosphere?

Ozone (O3)

What does albedo measure?

The fraction of incoming radiation that is reflected by a surface

Which of the following surfaces generally has the highest albedo?

Freshly fallen snow

What happens to Earth’s surface temperature when more radiation enters the surface than leaves it?

The temperature increases

What are the two major sources of downwelling radiation recived by Earth’s surface?

Downwelling solar and downwelling infrared radiation

Why does downwelling solar radiation reach its highest intensity around midday?

The Sun is highest in the sky, allowing sunlight to be more concentrated per unit area

How do clouds affect downwelling solar radiation and downwelling infrared radiation?

Clouds decrease downwelling solar radiation but increase downwelling infrared radiation

Why does a cloudy night tend to be warmer than a clear night?

Clouds emit infrared radiation toward Earth’s surface, helping keep it warm

According to Planck’s Law, when does Earth’s surface emit infrared radiation?

At all times, both day and night

What is the main source of upwelling radiation that leaves Earth’s surface?

Upwelling infrared radiation

What happens to upwelling infrared radiation as Earth’s surface temperature increases?

It increases

At a particular time, downwelling solar radiation is 800 W/m², downwelling infrared radiation is 270 W/m², and upwelling infrared radiation is 410 W/m². What is the net radiation and what happens to the surface temperature?

+660 W/m²; the surface warms

At nighttime, downwelling solar radiation is 0 W/m², downwelling infrared radiation is 240 W/m², and upwelling infrared radiation is 310 W/m². What happens to Earth’s surface temperature?

The surface cools because upwelling radiation is greater

Which of the following is the most abundant greenhouse gas in Earth’s atmosphere?

Water Vapor

According to Kirchhoff’s Law, why do greenhouse gases emt infrared radiation towards Earth’s surface?

Because gases that efficiently absorb radiation at a particular wavelength also efficiently emit radiation at that wavelength

What would Earth’s average surface temperature be without the greenhouse effect?

0F (-18C)

What has primarily caused atmospheric carbon dioxide concentrations to increase since the Industrial Revolution?

Human burning of fossil fuels such as coal, oil, and natural gas

What is the main scientific process responsible for Earth’s atmospheric greenhouse effect?

Greenhouse gases absorb and emit infrared radiation, including radiation directed back towards Earth’s surface