Earth's Atmosphere, Weather & Climate — Science

  1. Grade 6 — Earth's Four Spheres
  2. Grade 6 — The Water Cycle
  3. Grade 6 — The Atmosphere & Weather
  4. Grade 6 — Weather vs Climate
  5. Grade 9 — The Water Cycle

    ↑ Repeat of the G6 water-cycle rung, now inside a full weather system.

  6. Grade 9 — Air Masses, Fronts & Pressure
  7. Grade 9 — Reading Weather Patterns
  8. Grade 9 — Climate & the Greenhouse Effect

Apply it in a new setting

Problem 1

A weather map shows isobars (equal-pressure lines) packed tightly together over City A, while over City B, 200 km away, the isobars are spread far apart. Which prediction is best supported?
  1. City A will have stronger winds, because pressure changes sharply over a short distance there
  2. City B will have stronger winds, because spread-out isobars mean a bigger pressure gap
  3. Both cities will be windless, since isobars only show temperature
  4. City A will be warmer, because tight isobars trap heat
Hints

Isobars connect points of equal air pressure; their spacing shows how fast pressure changes with distance.

Wind is driven by pressure differences — a steep 'pressure hill' over a short distance drives faster wind.

Compare where the pressure change per kilometre is greatest.

Answer and explanation

City A will have stronger winds, because pressure changes sharply over a short distance there

Tightly packed isobars mean the air pressure changes a lot over a short distance — a steep pressure gradient.

A steeper pressure gradient drives stronger wind, just as a steeper slope makes a ball roll faster.

City A has the tightly packed isobars, so it has the stronger winds — A.

Problem 2

It is a clear morning in New York. The barometer has fallen steadily from 1018 mb to 1004 mb over six hours, and a large storm sits over Ohio, about 500 km to the west. Using how mid-latitude weather moves, what is the best forecast?
  1. Clear weather will continue, because the sky is clear right now
  2. Worsening weather is likely within a day, as falling pressure and the west-to-east flow bring the storm closer
  3. The storm will move west, away from New York, because storms avoid cities
  4. A cold, dry, sunny spell, because falling pressure means sinking air
Hints

In the mid-latitudes, the prevailing westerlies steer weather systems in one general direction.

Which direction is 'upwind' of New York — where tomorrow's weather is coming from?

A steadily falling barometer signals rising air, clouds, and storms; a rising one signals clearing.

Answer and explanation

Worsening weather is likely within a day, as falling pressure and the west-to-east flow bring the storm closer

Mid-latitude weather is steered west to east by the prevailing westerlies, so a storm over Ohio (to the west) is upwind and heading toward New York.

A steadily falling barometer means air is rising and clouds and storms are building, not clearing (rising pressure would mean clearing).

Both clues point the same way: worsening weather within a day — B.

Problem 3

An air mass forms and sits for days over the warm, humid surface of the Gulf of Mexico, then drifts north. Using the two-letter air-mass code, how should it be classified, and what weather does it most likely bring?
  1. Continental polar (cP): cold and dry
  2. Continental tropical (cT): warm and dry
  3. Maritime tropical (mT): warm and humid, often muggy with a chance of showers
  4. Maritime polar (mP): cold and humid
Hints

The first letter is moisture (continental = over land, dry; maritime = over ocean, moist).

The second letter is temperature (polar = cold; tropical = warm).

Where did it form — over water or land, at a warm or cold latitude?

Answer and explanation

Maritime tropical (mT): warm and humid, often muggy with a chance of showers

It forms over the ocean (the Gulf), so it is moist: maritime (m).

It forms at a warm, low latitude, so it is warm: tropical (T).

Maritime tropical (mT) air is warm and humid, bringing muggy conditions and possible showers — C.

Problem 4

A forecaster describes: 'High wispy clouds this morning will slowly lower and thicken through the afternoon, followed by many hours of light, steady rain, and then a gradual warming.' Which kind of front best matches this description?
  1. A warm front, where warm air slides slowly up over cold air, giving long, gentle precipitation
  2. A cold front, because cold fronts always bring rain
  3. A cold front, which brings a brief, intense storm and rapid clearing to colder air
  4. A stationary front, which never produces any clouds or rain
Hints

Compare the pace: is this a sudden, violent burst or a long, gradual change?

Cold fronts are steep and fast (brief intense storms, then colder); warm fronts are gentle and slow.

Note the gradual warming afterward — which air mass is taking over?

Answer and explanation

A warm front, where warm air slides slowly up over cold air, giving long, gentle precipitation

The slow, hours-long sequence of thickening clouds and light, steady rain is gradual, not sudden.

That gentle pace, plus the warming afterward, is the signature of a warm front (warm air riding slowly up over retreating cold air).

A cold front would instead bring a brief, intense storm and a quick clearing to colder air — so the answer is A.

Problem 5

Which statement correctly describes how the greenhouse effect warms Earth's surface?
  1. Greenhouse gases block incoming sunlight so it can't reach the ground
  2. Sunlight passes through and warms the ground, which radiates heat (infrared); greenhouse gases absorb and re-emit that outgoing heat, sending some back down
  3. Greenhouse gases produce their own heat by chemical reactions in the air
  4. The ozone hole reflects heat back onto the surface
Hints

Think about what greenhouse gases do to incoming sunlight versus outgoing heat.

Sunlight (shortwave) mostly passes through; the ground re-radiates energy as infrared (longwave) heat.

The 'blanket' traps outgoing heat, it does not create heat or block the incoming sunlight.

Answer and explanation

Sunlight passes through and warms the ground, which radiates heat (infrared); greenhouse gases absorb and re-emit that outgoing heat, sending some back down

Sunlight passes through the atmosphere and warms the ground, which then radiates the energy back upward as infrared heat.

Greenhouse gases absorb that outgoing heat and re-emit it in all directions, including back toward the surface, warming it further.

They do not block incoming sunlight or generate their own heat — the correct description is B.

Problem 6

During one unusually cold, snowy week, someone argues, 'This freezing week proves global warming isn't real.' What is the best scientific response?
  1. They are right; one cold week disproves any warming
  2. A single week is weather; climate and global warming are about long-term averages over decades, so one cold spell doesn't disprove a warming trend
  3. Global warming means every single day everywhere must be hotter than before
  4. Cold weather and climate are unrelated, so nothing can be concluded about anything
Hints

Recall the difference between weather (right now) and climate (long-term average).

Over how long a period is climate measured — a week, or decades?

Does a warming trend in the average rule out any individual cold spells?

Answer and explanation

A single week is weather; climate and global warming are about long-term averages over decades, so one cold spell doesn't disprove a warming trend

Weather is the day-to-day (or week-to-week) state of the atmosphere; climate is the long-term average over decades.

Global warming describes a rise in the long-term average temperature, which still allows for individual cold weeks.

So one cold week is just weather and doesn't disprove the climate trend — B.

Problem 7

A storm system is 480 km due west of a town and, carried by the prevailing westerlies, is moving steadily east at 30 km/h. If it keeps that speed and direction, about how many hours until it reaches the town?
Hints

The storm must cover the whole west-to-east distance at a steady speed.

Time = distance ÷ speed.

Divide 480 km by 30 km/h.

Answer and explanation

16 hours

Mid-latitude weather moves west to east, so the storm travels the full 480 km toward the town.

Time = distance ÷ speed = 480 km ÷ 30 km/h.

480 ÷ 30 = 16 hours.

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