Weather Exam 4 Draft 2

What is an urban heat island?

An urban area warmer than nearby rural surroundings, mainly because of physical changes in surface energy absorption, storage, and release.

Why do urban surfaces warm strongly?

Dark pavement, roofs, and buildings absorb and store heat. Less vegetation means less shade and evaporative cooling. Vehicles and buildings also release waste heat.

How do tall buildings add to urban heating?

Light reflected from one building can strike another and be absorbed. Repeated reflections increase the chances of absorption, especially in densely built downtown areas.

When is the urban–rural temperature difference especially noticeable?

Late evening and overnight, when built surfaces slowly release stored heat. Seasonal strength varies by city and weather. Hint: city surfaces keep releasing heat after sunset.

How can urban heating affect heat waves and nearby weather?

Extra urban warmth worsens heat waves. Urban heating also increases rising air; sometimes cloudiness and downwind storms increase, but these effects are not universal.

Which two long-term measurements mainly determine climate types?

Temperature and precipitation. Hint: How warm, and how wet? Climate describes long-term patterns; weather describes short-term conditions.

Which climate group is tropical or winterless?

A: warm year-round, usually near the equator. Some A climates are wet all year; others have wet and dry seasons. This is one of the instructor’s letter-choice examples.

Which climate group includes deserts and semiarid areas?

B: dry climates. Arid means desert; semiarid means less extreme dryness. B emphasizes moisture rather than a particular temperature. Desert → B is an instructor exam-style example.

What describes a C climate?

A mild midlatitude climate with distinct temperature seasons and relatively mild winters. Hint: Its winters are milder than those in D climates.

What describes a D climate?

A severe midlatitude or continental climate: long, very cold winters and shorter summers that can still be warm or hot. These climates mainly occur on Northern Hemisphere landmasses.

Which climate group is polar and includes ice caps?

E: cold throughout the year. Tundra has a short growing season; ice caps have persistent ice and snow. Polar or ice cap → E is an instructor exam-style example.

Which main climate group describes Georgia?

C. More specifically, humid subtropical Cfa: hot, humid summers, mild winters, and precipitation year-round. Georgia → C is an instructor exam-style example.

What basic C-climate patterns help with climograph reading?

Mediterranean: dry summers, wetter winters. Marine west coast: relatively cool or mild, with precipitation year-round. Humid subtropical: hot, humid summers, mild winters, and precipitation year-round. The instructor’s explicit testing priority is the main A–E groups.

What does a standard surface station model show, and where are its main values?

Weather at one place and time: temperature upper left, dew point lower left, cloud cover in the center, pressure upper right, and wind. Check the legend and units; other plot types may differ.

How do you decode sea-level pressure, such as station code 132?

For common classroom codes, keep leading zeros. Below 500, prefix 10; otherwise prefix 9. Put the decimal before the final digit. Example: 132 → 1013.2 mb. One mb equals one hPa; expect pressure near 1,000 mb.

What does a half-filled station-model circle mean?

Half the sky is covered by clouds: 4/8, or 50% cloud cover. The circle’s filling represents sky cover.

What does the wind shaft’s direction mean?

It points toward the direction the wind comes FROM. Example: A northwest shaft means wind from the northwest.

How do wind barbs show speed, and what do two long barbs plus one short barb mean?

Short barb = 5 knots; long barb = 10 knots; triangular pennant = 50 knots. Add the marks: 10 + 10 + 5 = 25 knots.

What does a climograph show?

A location’s typical temperature and precipitation, usually monthly averages across a year. The lecture uses a temperature line and precipitation bars; check the legend and units.

How do you recognize a climate pattern on a climograph?

Find the warmest, coolest, wettest, and driest periods. Example: Warm, dry summers and cooler, wetter winters suggest Mediterranean climate. One temperature peak alone cannot identify the subtype.

What does a meteogram show?

Observed or forecast weather at one location over hours or days. It can show temperature, dew point, pressure, precipitation, and wind.

Why compare several variables on a meteogram?

Read the axes and legend. Falling temperature, a wind shift, and changing pressure together can support a front-passage interpretation.

What does a surface weather map show, and what are isobars and isotherms?

Weather across many places at a mapped time. Isobars connect equal pressure; isotherms connect equal temperature. Hint: BAR = pressure; THERM = temperature.

What do closely spaced isobars indicate?

A stronger pressure gradient and generally stronger winds. Hint: Closer pressure lines usually mean stronger wind.

How do Northern Hemisphere surface highs and lows usually differ?

High: clockwise/outward flow, sinking air, often clearer skies. Low: counterclockwise/inward flow, rising air, possible clouds or rain if moist. These are tendencies. Surface winds do not follow straight high-to-low paths; friction allows them to cross isobars.

How do you identify cold and warm fronts, and what do they mean?

Cold: blue triangles; cold air advances into warmer air. Warm: red semicircles; warm air advances into colder air. Symbols point toward advance. Fronts can change clouds and precipitation without guaranteeing severe weather.

How do you identify stationary and occluded fronts?

Stationary: red semicircles and blue triangles on opposite sides; little movement. Occluded: purple triangles and semicircles on the same side; a cold front overtakes a warm front and lifts warm air from the surface.

What gives air masses their characteristics, and how do their code letters work?

Their source regions. Lowercase c = continental, relatively dry; m = maritime, relatively moist. Capitals describe temperature: T = tropical/warm; P = polar/cold; A = Arctic/very cold.

What do cP, cA, mP, mT, and cT mean?

cP: continental polar, cold/dry. cA: continental Arctic, very cold/dry. mP: maritime polar, cool or cold/moist. mT: maritime tropical, warm/moist. cT: continental tropical, hot/dry. 

What is atmospheric stability?

How air responds after vertical displacement. At the same altitude, a warmer parcel is generally less dense and tends to keep rising; a cooler parcel tends to sink back.

What is the environmental lapse rate?

The actual temperature change with height in the surrounding atmosphere. Compare it with the temperature of a moving air parcel.

How do dry and moist adiabatic lapse rates differ?

Dry: unsaturated rising air cools about 9.8°C/km, often rounded to 10°C/km, without exchanging heat with its surroundings. Moist: saturated rising air cools more slowly because condensation releases latent heat; the rate varies. Use the problem’s rate and rounding.

An unsaturated 25°C parcel rises 1 km at 10°C/km. What is its temperature, and how does it compare with 12°C or 18°C surroundings?

25 − 10 = 15°C. At the same height, 12°C surroundings favor continued rising; 18°C surroundings favor sinking back. Hint: Rise → cool; compare at the same altitude.

What is relative humidity, and how does temperature affect it?

Closeness to saturation at the current temperature, as a percentage. Without changing vapor content, cooling raises RH before condensation; warming lowers it. High RH does not always mean more water vapor.

What is dew point, and what does a small temperature–dew-point gap mean?

Dew point is the temperature at which cooling air becomes saturated at roughly constant pressure and moisture. Higher dew point generally means more vapor. A small gap between air temperature and dew point means high RH.

What is absolute humidity?

Water-vapor mass per volume of air, often measured in grams per cubic meter.

How do you use a psychrometer if dry bulb is 24°C and wet bulb is 19°C?

Evaporation cools the wet bulb. Subtract wet from dry: 24 − 19 = 5°C. Use the 5°C difference and 24°C dry-bulb reading in your course humidity table.

What does the wet-bulb difference tell you about moisture?

At the same dry-bulb temperature, a larger difference generally means drier air. Equal readings indicate saturation under normal measurement conditions.

What ingredients do thunderstorms need, and what provides lift?

Moisture, instability, and lift. Heating, fronts, mountains, and converging air can provide lift. Hint: M-I-L = Moisture, Instability, Lift.

Where and when are thunderstorms common?

Where warmth and moisture are available, often on warm-season afternoons but also at other times. They are especially frequent in the southeastern United States, including Florida.

What are the three stages of a single-cell thunderstorm?

Developing: updrafts and cloud growth. Mature: updrafts and downdrafts, with substantial precipitation. Dissipating: downdrafts dominate and the storm weakens. Hint: Up → up and down → down.

How do single-cell, multicell, squall-line, and supercell thunderstorms differ?

Single cell: one usually short-lived storm. Multicell: several cells at different stages. Squall line: storms arranged in a line. Supercell: persistent rotating updraft, called a mesocyclone. Supercells can produce tornadoes, but many do not.

What is vertical wind shear, and why does it matter?

A change in wind speed or direction with height. It helps organize many severe thunderstorms. Hurricanes organize more readily when wind shear is low.

What makes a rotating column of air a tornado?

A violently rotating column extends from a thunderstorm to the ground. Its circulation must reach the ground; its visible condensation funnel need not. Tornadoes occur in many regions, including the Southeast.

How is tornado strength rated?

The Enhanced Fujita scale uses damage surveys and estimated three-second gusts, not necessarily measured winds. It differs from the hurricane scale.