12.1: Where and how do hurricanes form?
- Page ID
- 44876
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\(\newcommand{\avec}{\mathbf a}\) \(\newcommand{\bvec}{\mathbf b}\) \(\newcommand{\cvec}{\mathbf c}\) \(\newcommand{\dvec}{\mathbf d}\) \(\newcommand{\dtil}{\widetilde{\mathbf d}}\) \(\newcommand{\evec}{\mathbf e}\) \(\newcommand{\fvec}{\mathbf f}\) \(\newcommand{\nvec}{\mathbf n}\) \(\newcommand{\pvec}{\mathbf p}\) \(\newcommand{\qvec}{\mathbf q}\) \(\newcommand{\svec}{\mathbf s}\) \(\newcommand{\tvec}{\mathbf t}\) \(\newcommand{\uvec}{\mathbf u}\) \(\newcommand{\vvec}{\mathbf v}\) \(\newcommand{\wvec}{\mathbf w}\) \(\newcommand{\xvec}{\mathbf x}\) \(\newcommand{\yvec}{\mathbf y}\) \(\newcommand{\zvec}{\mathbf z}\) \(\newcommand{\rvec}{\mathbf r}\) \(\newcommand{\mvec}{\mathbf m}\) \(\newcommand{\zerovec}{\mathbf 0}\) \(\newcommand{\onevec}{\mathbf 1}\) \(\newcommand{\real}{\mathbb R}\) \(\newcommand{\twovec}[2]{\left[\begin{array}{r}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\ctwovec}[2]{\left[\begin{array}{c}#1 \\ #2 \end{array}\right]}\) \(\newcommand{\threevec}[3]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\cthreevec}[3]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \end{array}\right]}\) \(\newcommand{\fourvec}[4]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\cfourvec}[4]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \end{array}\right]}\) \(\newcommand{\fivevec}[5]{\left[\begin{array}{r}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\cfivevec}[5]{\left[\begin{array}{c}#1 \\ #2 \\ #3 \\ #4 \\ #5 \\ \end{array}\right]}\) \(\newcommand{\mattwo}[4]{\left[\begin{array}{rr}#1 \amp #2 \\ #3 \amp #4 \\ \end{array}\right]}\) \(\newcommand{\laspan}[1]{\text{Span}\{#1\}}\) \(\newcommand{\bcal}{\cal B}\) \(\newcommand{\ccal}{\cal C}\) \(\newcommand{\scal}{\cal S}\) \(\newcommand{\wcal}{\cal W}\) \(\newcommand{\ecal}{\cal E}\) \(\newcommand{\coords}[2]{\left\{#1\right\}_{#2}}\) \(\newcommand{\gray}[1]{\color{gray}{#1}}\) \(\newcommand{\lgray}[1]{\color{lightgray}{#1}}\) \(\newcommand{\rank}{\operatorname{rank}}\) \(\newcommand{\row}{\text{Row}}\) \(\newcommand{\col}{\text{Col}}\) \(\renewcommand{\row}{\text{Row}}\) \(\newcommand{\nul}{\text{Nul}}\) \(\newcommand{\var}{\text{Var}}\) \(\newcommand{\corr}{\text{corr}}\) \(\newcommand{\len}[1]{\left|#1\right|}\) \(\newcommand{\bbar}{\overline{\bvec}}\) \(\newcommand{\bhat}{\widehat{\bvec}}\) \(\newcommand{\bperp}{\bvec^\perp}\) \(\newcommand{\xhat}{\widehat{\xvec}}\) \(\newcommand{\vhat}{\widehat{\vvec}}\) \(\newcommand{\uhat}{\widehat{\uvec}}\) \(\newcommand{\what}{\widehat{\wvec}}\) \(\newcommand{\Sighat}{\widehat{\Sigma}}\) \(\newcommand{\lt}{<}\) \(\newcommand{\gt}{>}\) \(\newcommand{\amp}{&}\) \(\definecolor{fillinmathshade}{gray}{0.9}\)Hurricane tracks and intensities
Figure 12.1.1 shows the tracks and intensities of all tropical cyclones on record. While the map may seem overwhelming, the main focus is on identifying the areas where colored lines, indicating the presence of a tropical cyclone at one time, are present. Therefore, focus on the areas where these colored lines are present.
Figure \(\PageIndex{1}\): Map of Tropical Cyclone Paths and Occurrences. (Public Domain; via NOAA Coastal Services). Alternative description of the image.
Tropical cyclones have historically formed across multiple ocean basins, with the highest concentration in the Atlantic, Caribbean, Gulf of Mexico, and western Pacific. The tracks illustrate how storms often cluster in warm, tropical regions and can travel across large portions of the ocean. Figure \(\PageIndex{1}\) also shows fewer storms in the South Atlantic and eastern South Pacific, highlighting that those areas rarely experience cyclones.
- Most tropical cyclones form in and near the tropics (near the equator), where there is plenty of ______.
- dry air
- cold air
- heat and moisture
- Tropical cyclones are common in almost every ocean basin, except for
- The North Atlantic Ocean
- The South Atlantic Ocean
- The Eastern South Pacific Ocean (near South America)
- b & c only.
- While many of these storms form in the tropics they _______ cross the equator and into the other hemisphere.
- always
- never
- This is because on the equator the ________ becomes zero, preventing air from “spinning” in cyclonic motion.
- Frictional Force
- Coriolis Force
- Gravitational Force
In addition to the ingredients mentioned in question 1, hurricanes need two more key ingredients in order to form:
- Warm Ocean Waters (80°F or higher): These are found along the east coasts of continents like North America, where warm ocean waters are carried from the equator towards the poles. On the west coasts of continents, cold ocean waters travel from the poles to the equator.
- Low Vertical Wind Shear: This occurs when winds change direction or speed with height. Vertical wind shear helps create tornadoes, but it shears off hurricanes, weakening them.
- Notice from Figure 12.1.1 that California, on the west coast of North America, gets very few hurricanes. This is likely because:
- California is too far away from the equator
- California has too much wind shear (which forms tornadoes)
- The North Pacific Ocean along the California coastline is too cold to support hurricanes