Weather and Water - Unit Test Study Guide

1) Meteorologya) The scientific study of Earth’s weatherb) Meteorologist is a person who studies the causes and effects of Earth’s weatherc) Weather is the condition of Earth’s atmosphere at a given time in a given place

2) Atmospherea) Layer of gases (air) that surround the Earth

i) Separated into layers based on the properties of each layerb) Air

i) Has mass and volumeii) Can be compressediii) Is a mixture of nitrogen (78%) and oxygen (21%)

3) Seasonsa) The Earth revolves around the sun

once every year (365 days)i) Summer – axis is leaning toward

the Sunii) Fall – axis is leaning toward

spaceiii) Winter – axis is leaning away

from the Suniv) Spring – axis is leaning toward

spaceb) The Earth rotates on its axis once a day (24 hours)

i) The axis is tilted at a 23.5˚ii) The axis always points toward the North Star

c) Sunlight strikes Earth surface (solar angle) and the light spreads out (Beam Spreading)i) High solar angle = high energy density = hotter days (seen at the equator)ii) Low solar angle = low energy density = cooler days (seen at the poles)

4) Heat Transfera) Molecular motion = heat

i) More molecular motion = increased heatii) Molecules in solids, liquids, and gases are moving

b) Radiationi) Transfer of electromagnetic energy without direct contactii) The sun is the major source of energy that drives our weatheriii) Sun gives off radiant energyiv) The land and water on Earth absorb the radiant energy

(1) Making the molecules move faster(2) Water heats up slower than the land, since it takes 5 times the amount of energy to heat water

than soilv) The atmosphere can absorb radiant energy directly

c) Conductioni) Energy transfer when two object comes in contact with each otherii) The heated surface of the Earth transfers its energy to the air it touchesiii) Energy is transferred molecule by molecule

d) Reradiationi) When the heated surface of the Earth gives off its energy to the atmosphere without direct contactii) When the surface releases it absorbed energy, it cools down

e) Convectioni) The movement of a fluid due to differences in

density because of temperature(1) Density is calculated is the equation

D = m / v(2) The unit for density is g / ml(3) Mass is the amount of matter in an object(4) Volume is the amount of space that object

takes upii) Only occurs in liquids and gasesiii) Seen in the convection chamber

(1) Air entered the chamber, cooled and sunk tothe bottom because it was denser

(2) Air traveled along the bottom to the candle(3) The candle heated the air, making it less dense and it rose(4) The air touched the top of the chamber which was cooled due to the ice, lost its energy, cooled

and became denser(5) The convection cycle began

iv) In atmosphere(1) Air is heated from the Earth’s surface(2) Air becomes warm, expands, and is less dense(3) Air rises(4) Air begins to cool, contracts and is denser(5) Air sinks(6) A convection cell begins

5) Water Cyclea) Evaporation

i) When liquid water turns into water vaporii) The liquid water gains energy (in the environment, the energy comes from the Sun)iii) Humidity

(1) The amount of water vapor in the air(2) Relative Humidity is the amount of

water vapor in the air compared to howmuch it can hold

b) Condensationi) When water vapor turns into liquid waterii) The water vapor loses energy (in the

environment, the energy is lost to theatmosphere)

iii) Dew Point(1) The temperature at which water changes from water vapor to liquid water (the air is

saturated)iv) Cloud formation

(1) Energy is transferred from the Sun to the water(2) The water evaporates into water vapor and enters the air(3) Water vapor cools as it rises(4) Water vapor condenses on a condensation nucleus(5) Clouds form

c) Precipitationi) Water that falls from clouds and reaches the ground

6) Watera) 97% of Earth’s water is ocean / sea (salt) waterb) The other 3% - rivers, lakes, atmosphere, groundwater, ice caps/glaciers, etc

7) Temperature, Volume, Density, Pressure

Temperature Air Volume Density Pressure

Cool Contracts & Falls ⇓ ⇑ ⇑

Warm Expands & Rises ⇑ ⇓ ⇓

8) Windsa) Warm air rising and cool air falling creates areas of low and high pressureb) Air moving from an area of high-pressure to an area of low-pressure is called wind

9) Local Windsa) Sea breeze

b) Land breeze

c) Mountain

breeze

d) Valley

breeze

10) Air Masses and Frontsa) A large body of air with the same temperature and moistureb) When two air masses collide, it is called a front

i) Front is the boundary that separates the air massesii) When cold air is pushing the warm air away – it is a cold frontiii) When warm air is sliding on top of the cold air – it is a warm front