Bobbling along in the sky , hot air balloons look like a fun way to spend a day. Before the invention of satellites or airplanes though, hot air balloons were used by scientists to study the atmosphere. Riding in their balloons, scientists gathered information about temperatures, humidity and even cosmic rays. For more than 150 years, balloons were considered cutting-edge atmospheric observatories.

What are some differences between research hot air balloons of the past and the scientific balloons we use today?

Text Reference 56-63Text Reference 56-63

1. Water makes up 75% of the surface of the earth

2. Water exists in three forms or phases (yup! Write it all!)

Solid - Ice

Liquid - Water

Gas - Vapor

Melting

Condensing

Freezing

Evaporating

3. Phase Changes of Water

a. Evaporation-Water molecules heat up and gain energy. They begin to move faster and change from the liquid to gas phase

Water molecules as a vapor

Water molecules as a liquid

A typical glass of water

3b. CondensationWater molecules slow down and lose

energy changing from a gas to a liquid

phase collecting on grass and objects in

the form of dew. If the temperature

falls below 0o C , it becomes frost.

Dew Point - the temperature at which water vapor condenses

3c. Transpiration

Water transferred from plants to the atmosphere as water vapor as they take in CO2

2. Water vapor from condenses into clouds

4. Deep ground water and runoff return water to the rivers, lakes, and oceans

3. Precipitation (rain, snow, hail) returns water to the soil

4. The Water Cycle

1. Heat energy from the sun warms surface water on the earth, causing it to evaporate and transpirate

5. HumidityA measure of the amount of water vapor in

the air• Warm air holds more moisture than cool air• Air feels cooler when the humidity is lower, the air

is more capable of evaporating water from sweat• Measured with an instrument called a

“Psychrometer”

• Saturation-the point at which evaporation and condensation are equal (warmer-higher; cold-lower)

Wet Bulb

Dry Bulb

6. Relative Humidity

The percentage of water vapor in the air compared to the maximum amount the air could hold. For example:

• If the air can hold 8 grams of water, and it has 8 grams in it, the relative humidity would be 100%• If the air can hold 8 grams of water, and

it has 4 grams in it, the relative humidity would be 50%

7. Dew Point• The

temperature at which condensation begins

a. Clouds form when the temperature falls below the dew point

b. Small particles of dust must be present for the water to condense

c. Three Basic Types: CumulusCumulus StratusStratus CirrusCirrus

C1-Cumulus (“heap”) Clouds

Thick and puffy, Thick and puffy, cotton candy clouds cotton candy clouds associated with fair associated with fair weatherweather

C2-CumulonimbusC2-Cumulonimbus clouds are clouds are vertically developed clouds that vertically developed clouds that

can yield lightning, hail, and can yield lightning, hail, and heavy rainfall.heavy rainfall.

Low level layer of Low level layer of clouds that clouds that often often covers the entire covers the entire sky.sky.

C4-Nimbostratus clouds are clouds are heavier stratus clouds that give heavier stratus clouds that give long periods of steady rain or long periods of steady rain or snow.snow.

C3-Stratus (“spread out”) (“spread out”) CloudsClouds

C5-CirrusC5-Cirrus - - Wispy, Wispy, feather feather cloudsclouds◦Only form at high levelsOnly form at high levels◦Made mostly of ice crystalsMade mostly of ice crystals◦Name means “curl of hair”Name means “curl of hair”

FogFog is a low-lying cloud at or is a low-lying cloud at or near the surface of the earthnear the surface of the earth

Common Types:• Rain-bigger than 0.5 mm •Drizzle-less than 0.5 mm• Freezing Rain- When rain strikes a cold surface and turns to ice•Sleet-Sleet-WhenWhen rain falls through rain falls through freezing air and turns to ice

SnowSnow - Ice crystals formed inside a - Ice crystals formed inside a cloud, form in the presence of little cloud, form in the presence of little windwind

Hail Hail - Pellets of ice greater than 5 mm - Pellets of ice greater than 5 mm in diameter. Form exclusively inside in diameter. Form exclusively inside cumulonimbus clouds and are cumulonimbus clouds and are associated with stormsassociated with storms

Hail forms in cumulonimbus clouds.

The End