UPCAT General Science (Extended) — Atmosphere, Weather & ClimateFlash Cards

What are the four main gases in Earth's atmosphere and their percentages?

Nitrogen (78%), Oxygen (21%), Argon (0.93%), and Carbon dioxide (0.03%). Nitrogen is essential for protein manufacturing in living things, while oxygen supports respiration and combustion processes.

Why does temperature decrease as you go higher in the troposphere?

Air becomes less dense at higher altitudes, so there are fewer molecules to absorb and retain heat from the Earth's surface. The troposphere is heated from below by the Earth's surface, not directly from the sun above.

In which atmospheric layer do commercial jets fly and why?

Lower stratosphere. Jets fly here because this layer is above most weather disturbances (which occur in the troposphere below) and has more stable air conditions for smooth flights.

What happens when warm humid air rises and cools?

Water vapor condenses below its saturation point, forming water droplets or ice crystals. This process creates precipitation (rain, snow) and is the basis for cloud formation and weather systems.

Why does wind blow from high pressure to low pressure areas?

Air naturally moves from areas of high density (high pressure) to areas of low density (low pressure) to equalize pressure differences. Cold air creates high pressure by sinking, while warm air creates low pressure by rising.

What is the Coriolis effect and how does it affect wind direction?

The Coriolis effect is the deflection of moving objects (including wind) caused by Earth's rotation. It causes wind to curve right in the Northern Hemisphere and left in the Southern Hemisphere, creating global wind patterns.

When does Hanging Amihan occur in the Philippines and what are its characteristics?

November to March. It brings cold temperatures with little rainfall and prevailing winds from the east (northeast). It blows from Siberia towards the Philippines, creating the dry season.

What causes sea breeze during daytime?

Land heats faster than water due to its lower heat capacity. This creates low pressure over land and high pressure over water. Air flows from high pressure (sea) to low pressure (land), creating sea breeze.

Which cloud type indicates fair weather and which indicates thunderstorms?

Cumulus clouds (fluffy, white, heap-like) indicate fair weather. Cumulonimbus clouds (tall, dark, towering) are 'thunderheads' that bring severe weather including lightning and tornadoes.

What happens when a cold front meets a warm air mass?

The cold air mass pushes under the warm air mass, forcing it to rise rapidly. This creates violent weather including heavy rains, thunderstorms, and strong winds as the warm air cools and condenses quickly.

Why does the mesosphere have the coldest temperatures in the atmosphere?

The mesosphere has few molecules to absorb solar energy, and it's too high to be warmed by Earth's surface. Additionally, it loses heat through radiation to space, making it the coldest atmospheric layer.

What is the difference between weather and climate?

Weather is the atmospheric conditions at a specific time and place (temperature, humidity, precipitation). Climate is the average weather conditions of a region over a long period (minimum 30 years).

Why do meteors burn up in the mesosphere?

Although the mesosphere has thin air, it's dense enough to create friction when meteors enter at high speeds. This friction generates intense heat that vaporizes the meteors, creating the 'shooting stars' we see.

What causes upwelling in oceans and why is it important?

Surface currents and winds cause deep, cold water to rise to the surface. This brings nutrient-rich water from ocean depths, supporting phytoplankton growth and creating productive marine ecosystems.

How does the ozone layer protect Earth?

Located in the stratosphere, the ozone layer absorbs harmful ultraviolet (UV) rays from the sun and converts them into heat. This protects living organisms from UV radiation damage.

What creates the three-cell circulation pattern (Hadley, Ferrel, Polar cells)?

Temperature differences between equator and poles create rising warm air at the equator and sinking cold air at the poles. Earth's rotation (Coriolis effect) divides this into three circulation cells in each hemisphere.

Why does land breeze occur at night?

At night, land cools faster than water due to its lower heat capacity. This creates high pressure over land and low pressure over water. Cool air flows from land to water, creating land breeze.

What percentage of Earth's water is freshwater and where is most of it found?

Only 2.8% of Earth's water is freshwater. Most freshwater is frozen in ice caps and glaciers. Only a small fraction exists as surface water (lakes, rivers) and groundwater that we can easily access.

What is polar creep and how does it distribute oxygen in oceans?

Cold, high-salinity water at the poles sinks and moves toward warmer regions. As it sinks, it carries oxygen from the surface to deeper ocean layers, helping distribute oxygen throughout ocean depths.

Why can the ionosphere reflect radio waves?

Solar radiation ionizes atoms and molecules in this region, freeing electrons. These free electrons can interact with radio waves and reflect them back to Earth, enabling long-distance radio communication.