ASVAB General Science part 3

What are solstices?

an event that occurs when Earth’s tilt causes one hemisphere to receive its maximum or minimum amount of sunlight.

What are the to types of solstices?

• Summer Solstice → longest day of the year

• Winter Solstice → shortest day of the year

Why do solstices occur?

They occur because Earth's axis is tilted 23.5° as Earth revolves around the Sun.

What is the summer solstice?

The day with the most daylight hours in a hemisphere.

Characteristics of summer solstice in the Northern Hemisphere.

• Occurs around June 21

• Northern Hemisphere is tilted toward the Sun

• Longest day of the year

• Beginning of summer

June = Northern summer

Characteristics of summer solstice in the Southern Hemisphere.

• Occurs around December 21

• Southern Hemisphere is tilted toward the Sun

• Longest day of the year

• Beginning of summer

December = Southern summer.

What is the winter solstice?

The day with the least daylight hours in a hemisphere.

Characteristics of winter solstice in the Northern Hemisphere.

Characteristics of winter solstice in the Southern Hemisphere.

• Occurs around June 21

• Southern Hemisphere is tilted away from the Sun

• Shortest day of the year

• Beginning of winter

What causes solstices?

Earth's tilt as it revolves around the Sun

What is weather?

The condition of the atmosphere at a specific place and time.

Examples of weather.

• Temperature

• Clouds

• Rain

• Wind

• Storms

• Snow

Weather describes what type of changes in the atmosphere?

Short-term changes.

What is climate?

The average pattern of weather in a specific region over a long period of time.

Climate is usually measured over:

30 years or more

Climate describes:

• Typical temperature

• Average precipitation

• Seasonal patterns

What factor influence climate?

• Latitude

• Elevation

• Ocean currents

• Distance from water

• Wind patterns

How does Latitude affect/influence climate?

Affects:

• Amount of sunlight received

• Temperature

• Length of daylight

General Pattern: What type of climate resides in the low latitude (near equator)?

Warmer climates

General Pattern: What type of climate resides in the high latitude (near poles)?

colder climates

Where does most weather occur in Earth's atmosphere?

Troposphere

The troposphere is:

• The lowest layer of Earth's atmosphere

• Where humans live

• Contains most atmospheric gases and water vapor

Why does weather occur in the troposphere?

• Clouds form

• Air moves

• Water cycles through evaporation and precipitation

What is an indicator of climate?

Latitude.

What is the hydrologic cycle?

(Also referred to as the water cycle)

The continuous movement of water:

• On Earth's surface

• Above Earth's surface (atmosphere)

• Below Earth's surface (groundwater)

The water cycle is powered mainly by:

• The Sun's energy (causes evaporation)

• Gravity (moves water downward through precipitation and runoff)

Water moves through the cycle while changing between its three states:

• Liquid → water

• Solid → ice/snow

• Gas → water vapor

What are the major processes of the hydrologic cycle?

1. Evaporation

2. Condensation

3. Precipitation

4. Transpiration

5. Runoff

6. Infiltration

7. Subsurface flow

8. Sublimation

9. Snow melt

10. Canopy interception

11. Advection

What is evaporation?

The process where liquid water changes into water vapor (gas).

How is evaporation caused and what are examples?

Cause:

• Heat energy from the Sun

Examples:

• Water from oceans, lakes, and rivers evaporates into the atmosphere.

What is condensation? Example?

When water vapor cools and changes into liquid water.

Example:

• Formation of clouds

What is precipitation?

When water falls from the atmosphere to Earth's surface.

Forms of precipitation include:

• Rain

• Snow

• Sleet

• Hail

What is transpiration?

The release of water vapor from plants into the atmosphere.

What is the process of transpiration?

• Plants absorb water through roots

• Water moves through the plant

• Water vapor exits through leaves

What is runoff?

Water flows across Earth's surface after precipitation.

What is infiltration?

Water soaks into the ground and enters soil or groundwater.

What is sublimation? Example?

The process where solid water (ice/snow) changes directly into water vapor without becoming liquid first.

Example:

• Snow disappearing in cold, dry conditions

What is snow melt?

The process where snow and ice change into liquid water.

Example:

• Mountain snow melting into rivers

What is a canopy interception? Example?

Rain or snow is temporarily caught by vegetation before reaching the ground.

Example:

• Rain sitting on tree leaves

What is a subsurface flow? Example?

Water moving underground through soil and rock.

Example:

• Groundwater traveling toward rivers or oceans

What is advection in the hydrologic cycle? Example?

The movement of water vapor through the atmosphere by wind.

Wind carrying clouds and moisture from one region to another

Hydrologic Cycle Process Order (Simplified)

• Sun heats water

• Evaporation → water vapor rises

• Condensation → clouds form

• Advection → winds move clouds

• Precipitation → water falls

• Runoff/Infiltration → water returns to oceans or groundwater

• Transpiration → plants release water vapor

• Cycle repeats

What is precipitation?

Water that falls from the atmosphere to Earth's surface after water vapor has condensed into water droplets or ice crystals.

Precipitation occurs when:

• Water evaporates into the atmosphere

• Water vapor cools and condenses into clouds

• Water droplets or ice crystals become heavy enough to fall

What are the forms of precipitation?

• Liquid Forms

• Frozen Forms

Rain is:

Liquid water droplets falling from clouds

Fog Drip is:

Tiny water droplets from fog collecting and falling onto surfaces

Snow is:

Ice crystals that form when water freezes in clouds

Hail is:

Balls of ice formed during strong thunderstorms

Sleet is:

Small ice pellets formed when raindrops freeze before reaching the ground

Where does precipitation occur in the water cycle?

Precipitation occurs after:

Evaporation → Condensation → Precipitation

What is the process of precipitation in the water cycle?

1. Sun heats water

2. Water evaporates into vapor

3. Vapor cools and condenses into clouds

4. Water falls as precipitation

5. Water returns to Earth's surface through runoff or infiltration

What must happen before precipitation can occur?

Condensation

Is evaporation precipitation?

No, evaporation moves water upward; precipitation brings water downward.

What is canopy interception?

Canopy interception occurs when precipitation (rain, snow, etc.) lands on plant surfaces instead of immediately reaching the ground.

What happens to water during canopy interception? Example?

• Remain on leaves, branches, and vegetation

• Evaporate back into the atmosphere

• Eventually drip down to the ground

Example:

• Rain collecting on tree leaves after a storm

What is advection?

The movement of water through the atmosphere, usually by wind.

What does advection transport? Example?

• Water vapor

• Clouds

• Moist air

Example:

• Wind carrying moisture from the ocean toward land

What process moves water vapor through the atmosphere?

Advection

What happens when rain lands on tree leaves before reaching the ground?

Canopy interception

What is infiltration?

The process where water moves from Earth's surface into the ground.

Infiltration occurs when:

Example?

• Rain or melted snow enters soil

• Water moves into underground spaces

• Some water becomes groundwater

Example:

• Rain soaking into soil after a storm

What is subsurface flow?

The movement of water through the ground beneath Earth's surface.

Subsurface flow can:

Example?

• Travel through soil

• Move through rocks and underground layers

• Feed rivers, lakes, and groundwater systems

Groundwater slowly moving underground toward a stream

What is the Hydrologic Cycle?

1. Precipitation → Water falls to Earth

2. Infiltration → Water enters the soil

3. Subsurface Flow → Water moves underground

4. Water may eventually return to:

   • Rivers

   • Lakes

   • Oceans

   • The atmosphere through evaporation

What is evaporation?

The process where liquid water changes into water vapor (gas).

This happens when water absorbs heat energy, usually from the Sun.

What is sublimation?

The process where solid water (ice or snow) changes directly into water vapor without becoming liquid first.

Process:

Solid ice/snow → Water vapor

What is the Hydrologic Cycle Connection for Evaporation?

Oceans, lakes, rivers → atmosphere

Both contribute to the formation of clouds through condensation.

What is the Hydrologic Cycle Connection for Sublimation?

Snow and ice → atmosphere

Both contribute to the formation of clouds through condensation.

Which process skips the liquid state?

Sublimation

What is the composition of Earth's atmosphere?

• Nitrogen (N₂) — 78%

• Oxygen (O₂) — 21%

• Argon (Ar) — about 1%

Small amounts of:

• Water vapor

• Carbon dioxide (CO₂)

• Dust particles

• Other trace gases and chemicals

What is used by humans and animals for respiration and supports combustion?

Oxygen

What is important for plant growth through the nitrogen cycle?

Nitrogen

What is part of the noble gases and is a inert (nonreactive) gas?

Argon

How much of Earth's atmosphere is nitrogen and oxygen?

• Nitrogen makes up about 4/5 of the atmosphere → 78%

• Oxygen makes up about 1/5 of the atmosphere → 21%

Together:

78% + 21% = 99%

The remaining 1% consists mainly of argon and trace gases.

What are the five main layers of Earth's atmosphere?

1. Troposphere

2. Stratosphere

3. Mesosphere

4. Thermosphere

5. Exosphere

As altitude increases:

• Air becomes thinner

• Pressure decreases

• Temperature changes depending on the layer

What is the stratosphere?

The second layer above Earth.

Stratosphere Characteristics:

• Extends to about 51 km above Earth

• Contains the ozone layer

• Ozone absorbs harmful ultraviolet (UV) radiation from the Sun

What is the mesosphere?

the third atmospheric layer.

Mesosphere Characteristics:

Example?

• Coldest layer of the atmosphere

• Meteors burn up here due to friction with air particles

Example:

• Shooting stars

What is the thermosphere?

The fourth layer of Earth's atmosphere.

Thermosphere Characteristics:

• Extremely thin air

• Very high temperatures because it absorbs high-energy solar radiation

• Where the International Space Station (ISS) orbits

Which layer of Earth’s atmosphere includes Aurora (Northern and Southern Lights) as well as where the International Space Station (ISS) orbits?

Thermosphere

What is the exosphere?

The outermost layer of Earth's atmosphere.

Exosphere Characteristics:

• Extends up to about 10,000 km

• Extremely low density

• Mainly made of:

  • Hydrogen

  • Helium

It gradually transitions into outer space.

Where do meteors burn up?

Mesosphere

What layer contains mostly hydrogen and helium?

Exosphere

What are high clouds

Clouds that form at high elevations in the atmosphere.

At what altitude do high clouds occur?

Approximate altitude:

5,000–13,000 meters
(about 16,000–43,000 feet)

What are high clouds made up of?

Ice crystals

What are cirrus clouds?

THIN AND WISPY CLOUDS THAT LOOK LIKE:

• Feathers

• Hair strands

• A horse's tail ("mare's tails")

What are the characteristics of Cirrus clouds?

• Very high altitude

• Made mostly of ice crystals

• Usually indicate fair weather, but can appear before weather changes

What are cirrocumulus clouds?

Small, white, rounded clouds that appear in groups.

What are the characteristics of cirrocumulus clouds?

What are they made up of?

• Small puffs

• Ripples

• Rows or patches

• Often called a "fish scale" pattern

Made up of: Ice crystals

What are cirrostratus clouds?

Clouds that are thin, sheet-like clouds that spread across much of the sky.

What are the characteristics of Cirrostratus clouds?

• Can cover the entire sky

• Often create halos around the Sun or Moon

• Made of ice crystals

Which clouds form a sheet across the sky?

Cirrostratus

Why are high clouds often made of ice?

Temperatures are very cold at high altitudes