Intro to Weather and Climate Review

Intro to Weather and Climate

Chapter Objectives

By the end of this chapter, you should be able to:

List three ways the scientific method can be applied to studying the atmosphere and weather.
Outline the sequence of changes in nitrogen ( $N<em>2$ ), oxygen ( $O</em>2$ ), and water vapor ( $H_2O$ ) over Earth’s history.
Explain the role of gases (including water vapor ( $H<em>2O$ ), carbon dioxide ( $CO</em>2$ ), oxygen ( $O_2$ ), and other greenhouse gases) and pollutants in Earth’s atmosphere.
Describe how air density and air pressure are determined and how they vary as you move upward through Earth’s atmosphere.
Describe the layers of the atmosphere, including their altitudes, temperatures, compositions, and functions.
Differentiate between weather and climate.
Interpret a weather map, applying storm types and concepts such as low pressure, high pressure, and fronts.
List the positive and negative effects of climate and weather on human health, agriculture, infrastructure, and the economy.

The Scientific Method and Atmospheric Study

Foundation of Understanding: Our understanding of the atmosphere and weather is built on knowledge obtained using the scientific method.
Core Principles: Involves posing a question, proposing a hypothesis, predicting the implications of an accurate prediction, and performing tests.
Quantitative Testing: Hypotheses must be rigorously tested using quantitative methods. This includes employing weather instruments and conducting laboratory experiments.
Modern Application: Over the past $60$ years, computerized numerical models have been extensively used to test weather and climate forecasts and other atmospheric phenomena.
Distinction from Anecdotal Knowledge: Common weather sayings, such as “Red sky at morning, sailor take warning; red sky at night, sailors delight,” arise from years of observation and may hold some validity. However, they are not considered products of the scientific method because they have not been validated in a standard, rigorous way.
Hypothesis Confirmation: A hypothesis is confirmed as correct only after passing a series of quantitative tests. This validation involves carrying out tests to see if predictions are accurate. While laboratory tests allow for replication, studying Earth's single atmosphere presents unique challenges for replication.

Weather, Climate, and Meteorology

Weather: Defined as the state of the atmosphere in a specific location and time. It is a dynamic system that constantly changes, often in a matter of minutes.
Climate: The accumulation of daily and seasonal weather events over longer periods. Examples include the typical summer heat waves or cold spells of winter in a given region.
?\ Elements of Weather: These are the key variables that describe the state of the atmosphere:
- Air Temperature
- Humidity
- Clouds
- Precipitation
- Wind Direction
- Wind Speed (Gusts)
- Visibility
- Air Pressure

Weather Observation and Remote Sensing Tools

Several tools are used to observe and measure atmospheric conditions:

Satellite: Provides broad, overhead views of large-scale weather systems and cloud cover.
Weather Radar: Detects precipitation, its intensity, and movement, and can infer storm structure.
Rawinsondes: Balloon-borne instruments that measure temperature, humidity, and atmospheric pressure at various altitudes.
Surface Weather Observations: Data collected from a network of ground-based stations.
Aircraft Observations: Data collected by commercial and research aircraft at various flight levels.
Lightning Detection Networks: Systems that detect and track lightning strikes.
Buoys: Ocean-based instruments that measure sea surface temperature, air temperature, pressure, wind, and wave height.
Human Observation Networks: Volunteer networks like SkyWarn and CoCoRaHS augment automated observations with local, ground-truth reports.
ASOS/AWOS Configurations: Automated Surface Observing System (ASOS) and Automated Weather Observing System (AWOS) include:
- Anemometer/Wind Vane for wind speed and direction.
- Visibility Sensor.
- Precipitation Discriminator.
- Thermometer and Hygrometer.
- Freezing Rain Sensor.
- Rain Gauge.
- Ceilometer for cloud base height.
- Limitations: ASOS/AWOS typically cannot directly observe hail, tornadoes, or ice pellets/sleet.
- Augmentation: Human observers or additional specialized sensors are often required to report these phenomena, along with severe thunderstorms.

Meteorology: The Study of the Atmosphere's History

Meteorology is the scientific study of the atmosphere and its phenomena. Its development has involved centuries of observations and technological advancements:

$340$ B.C.: Aristotle's Meteorologica, one of the earliest known treatises on weather.
$1593$ : Thermometer invented by Galileo, allowing for quantitative temperature measurement.
$1643$ : Barometer invented by Torricelli, enabling atmospheric pressure measurement.
$1664$ : Hygrometer developed by da Vinci/Folli, for measuring humidity.
$1843$ : Telegraph's invention revolutionized weather communication, allowing rapid transmission of observations.
$1846$ : $4$ -cup Anemometer invented by Robinson, for measuring wind speed.
$1849$ : Smithsonian Institution began organizing a network of volunteer weather observers.
$1870$ : The Signal Corp / Department of War established a national weather warning service in the U.S.
$1891$ : A civilian U.S. Weather Bureau was established, succeeding the Signal Corp's weather service.
$1920$ : The concept of air masses and weather fronts was developed, greatly advancing weather theory.
$1936$ : A significant Mississippi tornado outbreak highlighted the need for improved forecasting and warnings.
$1940$ s: Upper air balloon (rawinsonde) observations became widespread, providing vital data from higher altitudes.
$1950$ s: The advent of computers enabled numerical weather prediction models.
$1957$ : Weather radar was introduced, allowing for real-time tracking of precipitation.
$1960$ : The first weather satellite (Tiros $1$ ) was launched, providing global atmospheric views.
$1970$ : The U.S. Weather Bureau was reorganized and renamed the National Weather Service (NWS).
$1974$ : The Super Outbreak of tornadoes underscored the ongoing challenges and developments in severe weather forecasting.
$1980$ s: Doppler weather radars were implemented, capable of detecting wind velocity within storms.
$1980$ s: Lightning detection systems became operational.
$1990$ s: Automated Surface Observing System (ASOS) networks were deployed.
$1990$ s: The NWS underwent significant modernization, integrating new technologies.
$2000$ s: Dual-polarization Doppler weather radar was introduced, providing more precise information about precipitation types.
$2011$ : The April/May Super Outbreaks marked another period of exceptionally severe tornado activity.

Stanley Gedzelman's Seven Causes of Weather

Professor Stanley Gedzelman (CCNY) outlined fundamental causes that drive weather phenomena:

Variable Solar Heating: The Sun's heating on Earth varies significantly with geographical location and with the seasons.
Temperature Gradients Drive Wind: Differences in air temperatures across the Earth's surface generate pressure differences, which in turn cause wind.
Earth's Rotation Modifies Wind Patterns: The rotation of the Earth applies a Coriolis force that deflects and twists simple wind patterns, leading to the formation of spirals associated with high and low-pressure systems.
Cooling Air Causes Precipitation: Since colder air can hold less moisture, precipitation is generally initiated by the cooling of air, which leads to condensation.
Pressure Always Decreases with Height: A fundamental principle is that atmospheric pressure consistently decreases as altitude increases.
Adiabatic Temperature Changes: Processes involving changes in air pressure directly affect temperature:
- The process of decreasing air pressure (e.g., as air rises) causes temperatures to drop (adiabatic cooling).
- The process of increasing air pressure (e.g., as air sinks) causes temperatures to rise (adiabatic warming).
Vertical Air Movement Dictates Sky Conditions:
- Rising air, typically associated with low-pressure systems, leads to the formation of clouds and precipitation.
- Sinking air, typically associated with high-pressure systems, leads to clear skies and fair weather.

A Satellite's View of the Weather

Geostationary Satellites: These satellites orbit at the same speed as the Earth's rotation, allowing them to remain over a fixed point on the surface. This provides a continuous observation of weather events.
Global Perspective: Weather satellites offer a comprehensive view of global weather patterns, illustrating features such as lines of longitude, parallels of latitude, middle-latitude storms, hurricanes, and thunderstorms.

Weather Maps and Interpretation

Types of Maps: Weather information is presented on various maps, including Surface Maps (depicting conditions at ground level) and Upper Air Maps (showing conditions at specified atmospheric levels).
Isolines / Isopleths: These are lines on a map that connect points of equal or constant values of a given meteorological property (with respect to place and time).
- Isobars: Lines of equal atmospheric pressure.
- Isallobar: Lines of equal pressure change over a specific time period.
- Isotherm: Lines of equal temperature.
- Isodrosotherm: Lines of equal dew point temperature.
- Isohyet: Lines of equal precipitation amount.
- Isotach: Lines of equal wind speed.
Key Weather Map Elements:
- Wind: Indicated by wind barbs, showing both wind direction (the direction from which the wind is blowing) and wind speed.
- Fronts: Represent boundaries between air masses with different temperature and moisture characteristics. Common types include cold fronts, warm fronts, stationary fronts, and occluded fronts.
- Pressure Differences: Horizontal pressure differences are the fundamental cause of wind, creating a force that initiates air movement from areas of higher pressure towards areas of lower pressure.
- Deflection of Wind: The Earth's rotation causes the Coriolis effect, which deflects moving air (and other moving objects) to the right in the Northern Hemisphere and to the left in the Southern Hemisphere, influencing storm systems and global wind patterns.
Practical Interpretation: Interpreting a weather map allows for predicting conditions, assessing travel impacts (e.g., potential flight delays due to storms), and making personal preparedness decisions (e.g., whether to bring an umbrella).

Weather and Climate in Our Lives

Weather and climate play a profoundly important role in human lives, dictating numerous aspects of our existence:

Clothing: Daily clothing choices are directly influenced by prevailing weather conditions.
Agriculture: Climate and weather are critical determinants for crop growth, irrigation needs, pest control, and livestock management, fundamentally impacting food security.
Utilities: Heating and cooling demands for homes and businesses are primarily driven by temperature and other weather elements, affecting energy consumption and infrastructure.
Health Effects: Weather extremes can lead to various health issues, including heat stroke, hypothermia, respiratory problems exasperated by air quality, and the spread of vector-borne diseases.
Severe Weather Impacts: Phenomena like hurricanes, tornadoes, floods, droughts, and blizzards can cause widespread destruction to infrastructure, significant economic losses, and pose severe threats to human life.
Fog: Reduces visibility, significantly impacting transportation (road, air, and marine) and safety.
Real-World Examples: Images illustrate the devastating impacts of severe weather events, such as infrastructure damage from hurricanes, the destructive power of tornadoes, and the widespread disruption caused by floods.

National Weather Service (NWS) Alerts

Sole Source: The National Weather Service (NWS) is the sole official source for weather watches, advisories, and warnings in the United States.
Weather Watch: Issued when conditions are favorable for a particular hazardous weather event (e.g., a