A brown haze develops over a city after heavy afternoon traffic on a hot, sunny day. Which type of smog is most likely forming?

A gray, smoky haze blankets a coal-burning industrial district during cool, damp weather. Which type of smog is most likely present?

During a heat wave, nitrogen oxides and gasoline vapors react in bright sunlight above a metropolitan area. What type of smog results?

A power plant burning sulfur-rich coal releases smoke and sulfur dioxide into moist, cool air. Which smog type best matches these conditions?

An air-quality monitor records its highest ground-level ozone on a clear, hot day with dense commuter traffic. What type of smog is this evidence for?

In winter, homes and factories burn large amounts of coal, producing a sulfurous gray haze with soot. What type of smog is most likely?

A city has a brownish, eye-irritating haze on a sunny afternoon after emissions from cars accumulate. Identify the smog type.

Cool fog mixes with soot and sulfur dioxide from nearby coal furnaces. What kind of smog does this describe?

Which pair of pollutants can react in sunlight to form ground-level ozone, the main component of photochemical smog?

A city targets tailpipe emissions to reduce photochemical smog. Which device on modern cars is designed to cut these smog-forming emissions?

Ground-level ozone is not emitted directly from a smokestack. It forms in the air when other pollutants react in sunlight. What type of pollutant is it?

Which pollutant combination is most characteristic of industrial smog from uncontrolled coal combustion?

A coal-fired boiler emits fly ash and sulfur dioxide. Which device is designed to remove the fly ash particles before they leave the stack?

A community switches from high-sulfur coal to a lower-sulfur fuel to reduce industrial smog. Which device could a coal plant add instead to remove sulfur dioxide from its exhaust?

Warm air settles above cooler air near the ground for several days. What happens to pollutants emitted at street level?

Which temperature arrangement defines a thermal inversion near Earth's surface?

Why can a thermal inversion raise pollution concentrations at breathing height?

Morning sunlight warms the cool air at the bottom of a valley enough to end an inversion. What change is most likely for trapped pollutants?

A factory plume rises until it reaches a warm layer above cooler surface air, then spreads sideways. What is the warm layer acting as?

At dawn, air at ground level is 6 °C while air 300 meters higher is 11 °C. What atmospheric condition does this vertical pattern indicate?

A city lies in a basin surrounded by mountains. Why can this geography worsen smog during stagnant weather?

At night, cold dense air drains into a valley while warmer air remains above it. Why does this setting often have poor air quality by morning?

An industrial facility is upwind in a long, narrow valley, and a town farther along the valley has elevated pollution. How can valley geography contribute?

A coastal basin receives a daytime sea breeze that carries urban emissions inland toward surrounding hills. How can this geography intensify smog?

Tall buildings line a narrow downtown street with light winds and heavy traffic. Why might pollutant concentrations be high at street level?