Weather Exam 3

What is urban climatology?

The study of climates and climate changes associated with built environments.

What is an urban heat island (UHI)?

An urban area that is warmer than surrounding rural areas, especially noticeable at night.

When is a UHI often strongest?

At night, when cities retain stored heat while rural areas cool more rapidly.

Why do cities store more heat?

Urban materials absorb more heat and release it more slowly.

What is anthropogenic heat?

Heat from human activities such as cars, heating/AC, and industry.

How does pollution contribute to the UHI?

Pollution absorbs radiation emitted by the city and re-emits it back toward the city, similar to the greenhouse effect.

Why does reduced evapotranspiration increase urban temperature?

Impervious surfaces reduce soil moisture and plant transpiration; evaporation normally cools the environment.

Why does reduced wind speed increase urban temperature?

More friction reduces wind and therefore reduces heat transport away from the city.

What is an urban cool island (UCI)?

A city that is cooler than surrounding rural areas, especially during daytime.

How does the UCI compare with the UHI?

The UCI is generally not as large as the UHI.

Why does the UHI matter?

It can worsen heat waves, increase energy use, and contribute to pollution problems.

What major heat-wave example is in the slides?

Chicago, 1995, where about 700 people died.

How can cool roofs reduce urban heat?

They reflect more solar radiation and absorb less heat.

How can green roofs reduce urban heat?

Vegetation provides shading and evapotranspiration.

How can urban vegetation reduce heat?

Through shade and evapotranspiration.

What are NAAQS?

National Ambient Air Quality Standards set by the EPA for pollutant concentrations that protect health and the environment.

What does a primary air-quality standard protect?

Public health, with a margin for safety.

What does a secondary air-quality standard protect?

Public welfare, including crops, infrastructure, water, economy, and comfort.

What is a major source of sulfur dioxide?

Combustion of coal and oil.

How can coal power plants reduce sulfur dioxide?

Using scrubbers.

What are major sources of nitrogen oxides?

Car exhaust and other fossil-fuel combustion.

What is acid rain?

Precipitation made more acidic by atmospheric pollution; the slides give pH about 4.

What is neutral pH?

pH 7.

What is surface ozone?

Ozone near Earth's surface that is a harmful secondary pollutant; it is NOT the ozone layer.

Why is surface ozone harmful?

It is a strong oxidizer that damages plants, eyes/lungs, rubber, paint, and plastic.

How is surface ozone produced?

Through sunlight-driven photochemical reactions involving NOx, oxygen, and other reactive compounds.

Why is Los Angeles a classic smog example?

Traffic, sunshine, mountains, and temperature inversions combine to trap and produce pollution.

How does a temperature inversion worsen air pollution?

Stable air limits vertical circulation and traps pollutants near the surface.

What conditions characterize the LA inversion example?

Cold surface temperatures, relatively cold ocean water, very stable air, and little circulation.

What is particulate matter?

Solid or liquid particles suspended in a gas.

What is PM10 associated with?

Visibility and respiratory effects.

What is PM2.5 associated with?

Cardiopulmonary effects.

Why are lead and mercury important pollutants?

They are neurotoxins and can bioaccumulate.

What are sources of lead and mercury listed in the slides?

Combustion, paint, mining, and manufacturing.

What does carbon monoxide do?

It reduces oxygen delivery and can cause death at extreme concentrations.

What is a major source of carbon monoxide?

Combustion, mostly mobile sources.

What are CFCs?

Chlorofluorocarbons formerly used in products such as refrigerants and propellants.

How do CFCs damage the ozone layer?

Released chlorine can catalytically destroy multiple ozone molecules.

Why is ozone-layer depletion harmful?

It exposes Earth's surface to more harmful UV radiation.

What is the ozone hole?

A region of severe seasonal ozone depletion, not a literal hole.

When is the ozone hole greatest?

Southern Hemisphere spring.

Why does ozone destruction accelerate in spring?

Chlorine accumulates during winter, then spring sunlight catalyzes ozone destruction.

What is the Montreal Protocol?

An international agreement to phase out CFCs.

What happened after the Montreal Protocol?

Ozone depletion leveled off, with recovery projected around the 2050s in the slides.

What is weather?

Short-term atmospheric variations, from minutes to days.

What is climate?

Slowly varying characteristics of the atmosphere-hydrosphere-land system, typically described using averages over a month or more.

What is the basic weather vs. climate distinction?

Weather is short-term; climate describes longer-term patterns and averages.

What is a climate normal?

A 30-year mean.

How often are climate normals updated?

Every decade.

What is a climate control?

A factor that influences the climate of a location.

Why is latitude a climate control?

Solar radiation varies with latitude and influences temperature.

How does proximity to water affect climate?

It can increase precipitation and reduce the temperature range.

How do mountains affect climate?

They enhance precipitation, create downwind rain shadows, and cool temperatures.

How do oceans affect climate?

Ocean current direction and source region influence local climate.

How does atmospheric circulation affect climate?

It transports temperature and moisture and affects convergence/divergence and storm tracks.

What is the Köppen climate classification system?

A system for classifying climates into major groups based on climate characteristics.

What does Köppen A represent?

Tropical climates.

What A climates are shown?

Rainforest (Af), such as Singapore, and monsoon (Am), such as Sittwe, Myanmar.

What does Köppen B represent?

Dry climates.

What B climates are shown?

Hot desert (BWh), such as Yuma, AZ, and hot steppe (BSh), such as Cloncurry, Australia.

What does Köppen C represent?

Temperate climates.

What C climates are shown?

Mediterranean (Csa/Csb), such as Los Angeles, and humid subtropical (Cfa/Cwa), such as Dallas.

What does Köppen D represent?

Continental climates.

What D climates are shown?

Humid continental (Dfa/b, Dwa/b), such as Shippensburg, PA, and subarctic (Dfc/d, Dwc/d), such as Fairbanks, AK.

What does Köppen E represent?

Polar climates.

What E climates are shown?

Tundra (ET), such as Utqiagvik, AK, and ice cap (EF), such as Summit Camp, Greenland.

What evidence of climate change is shown?

Changes in global temperature, ocean heat content, spring snow cover, mountain glaciers, continental ice sheets, Arctic sea ice, and global sea level.

What has happened to global sea level?

It has risen.

What causes sea-level rise?

Thermal expansion of seawater and addition of water from melting land ice.

What is paleoclimate?

Climate information from Earth's past reconstructed using evidence rather than modern direct measurements.

What are proxy data?

Preserved physical information used to reconstruct past climate.

Why are proxy data useful?

They extend climate records beyond the period of direct measurements.

What climate-change timescale is associated with plate tectonics in the slides?

Tens of millions of years.

Does plate tectonics explain the recent warming emphasized in the slides?

No, according to the slide.

What are Milankovitch cycles?

Long-term changes in Earth's orbital/rotational geometry that affect climate; the slides identify a roughly 100,000-year cycle.

Do Milankovitch cycles explain the recent warming emphasized in the slides?

No, according to the slide.

How much does the solar constant vary in its 11-year cycle?

About 0.1% up and down.

Does the 11-year solar variation explain the recent warming emphasized in the slides?

No, according to the slide.

What does the greenhouse-gas theory explain?

Warming associated with increasing greenhouse gases and changes in Earth's energy balance.

What supports the greenhouse-gas theory according to the slides?

The geologic record and computer simulations; the slides call it a robust theory.

What are greenhouse gases?

Gases that absorb and re-emit outgoing terrestrial infrared radiation, affecting Earth's energy balance.

Why does increasing CO₂ warm climate?

More CO₂ increases absorption of outgoing longwave radiation and changes the energy balance toward warming.

What do the atmospheric CO₂ slides show?

A long-term rise in atmospheric CO₂ and a strong human contribution to the increase.

What is a climate model?

A computer program that represents environmental processes with equations and simulates climate over time.

How have climate models improved?

They include more processes, better process understanding/math, higher spatial resolution, and greater computing power.

Do climate models stop being relevant at 2100?

No; the slides emphasize warming does not simply stop in 2100.

What are Shared Socioeconomic Pathways (SSPs)?

Scenarios representing different possible socioeconomic and emissions futures used in climate modeling.

Why do emissions scenarios produce different future climate projections?

Different greenhouse-gas emissions produce different radiative forcing and therefore different modeled warming and impacts.

What future precipitation material is shown?

Model-predicted precipitation and U.S. precipitation extremes, showing potential changes in precipitation patterns.

Why is some future sea-level rise already locked in?

Time lags mean CO₂ emissions lock in warming, and warming locks in additional sea-level rise.

What happens if all fossil fuels are burned, according to the slides?

About 11°C (20°F) warming and more than 200 ft of sea-level rise.

What are examples of future climate impacts?

Wide-ranging changes involving temperature, precipitation, sea level, ice, ecosystems, and other systems.

What is a climate tipping point?

A threshold beyond which a climate system can undergo a sudden and significant shift.

What is a possible thermohaline shutdown?

A tipping-point change in ocean circulation that the slides associate with the possibility of inducing an ice age.

What could disintegration of the West Antarctic or Greenland ice sheets cause?

Major sea-level rise.

What is Amazon rainforest dieback?

Potential large-scale rainforest loss associated with deforestation and drying, with ecological and economic effects.

Why is thawing permafrost a concern?

It can release large amounts of greenhouse gases, including methane, potentially amplifying warming.

How could the Indian monsoon become a tipping point?

Changes in timing and amount could cause major flooding and economic consequences.