Atmosphere and Air Pressure Study Guide

This guide does NOT count for extra credit. Answer the questions on a separate sheet of paper.

  1. Define these parts of the water cycle.

·  Accumulation – (reservoirs) places where water builds up

·  Condensation – gaseous water forms liquid water after cooling

·  Evaporation – liquid water forms gaseous water after heating

·  Precipitation – gaseous water condenses in the atmosphere, causing rain, hail, snow, sleet, etc.

·  Runoff – precipitation over land collects and flows to lower, larger bodies of water

·  Transpiration – plants lose water from their leaves through small pore-like openings

·  Groundwater – water stored in the ground in aquifers, reservoirs, caverns, etc.

  1. The amount of water in Earth’s atmosphere: changes/does not change. (Circle One)

Does not change

  1. What causes the temperature to decrease with altitude in the troposphere?

The Earth heats the air, so the farther we get from the heat source, the cooler the air feels.

  1. What causes the temperature to increase with altitude in the stratosphere?

The stratosphere contains ozone, which absorbs harmful light from the Sun. By absorbing this light energy, the molecules speed up (heat up).

  1. In what layer of the atmosphere do each of the following appear?

·  Weather troposphere

·  Ozone stratosphere (ozonophere)

·  International space station thermosphere (ionosphere)

·  Radio waves thermosphere (ionosphere)

·  People troposphere

·  Clouds troposphere

·  Unmanned satellites thermosphere (exosphere)

·  Aurora borealis thermosphere (ionosphere)

  1. What is the composition of the atmosphere? (In terms of elements)

Mostly nitrogen (78%), with smaller parts oxygen (21%) and other gases (<1%)

  1. In what layer does the majority of the atmosphere’s mass exist? What holds the atmosphere near the Earth’s surface?

Troposphere (80% of the atmosphere’s total mass), gravity

  1. In your own words, describe how air pressure decreases as you climb a mountain. Use the word density.

Air pressure decreases as you climb a mountain because the particles are farther apart. Gravity pulls air molecules toward the ground, so they are densest at the ground. As we move higher up, air pressure decreases because molecules are not packed as close to each other (less dense). This is why air is described as “thinner” near mountaintops and why mountain climbers sometimes carry oxygen with them in tanks.

  1. Describe how a plane’s wing provides the lift for flight using the terms air pressure and wind speed.

A plane’s wing is shaped so that wind traveling over the top has a higher wind speed. Higher wind speed gives a lower air pressure, since molecules don’t touch surfaces as often. The underside of the wing has lower wind speed (higher pressure – more time to run into the wing’s surface), and it pushes up on the wing – toward the lower pressure. This provides a net upward push that lifts the wing.

  1. Why does water stay inside of a straw when you plug one end with your finger?

The water leaving the straw has to have something to replace it. When your finger isn’t on the straw and you lift it, water drains from the straw because air rushes in the top as water rushes out the bottom. When you have your finger on the straw, water tries to drop out. However, this means the air in the straw would be at a lower pressure. The air outside pushes up on the water at this point, keeping it inside the straw. Until air can get in behind the water to equalize the pressures, the water will stay in the straw.
Interestingly, if you cover your finger BEFORE you put it in the water, you will find that water cannot enter the straw for the same reason. If you lift the straw out, no water will be in the straw. This same principle was used in the creation of the diving apparatus known as a “diving bell.”