[Tex/LaTex] how to put caption (a) below 2 pictures

captions

enter image description here

I am rephrasing my question…
I want to obtain attached Image.. I have coded as below.. But I do not obtain required output.. Can you help me modify my code?

\begin{document}
\begin{figure}[ht]
\begin{subfigure}{\textwidth}
\centering
\includegraphics[width=6cm]{c1.eps}
\includegraphics[width=6cm]{c2.eps}
\caption{}%{V} \label{fig:a}
\end{subfigure}
\begin{subfigure}{\textwidth}
\centering
\includegraphics[width=6cm]{c3.eps}
\includegraphics[width=6cm]{c4.eps}
\caption{}%{P} \label{fig:b}
\end{subfigure}
\caption{Variation} \label{fig:wind_speed}
\end{figure}
\end{document}

Best Answer

Would this be what you seek? Use of subfigure environment from subcaption package

Update: second attempt

enter image description here

Code

\documentclass{article}
\usepackage{graphicx}
\usepackage{subcaption}

\begin{document}

\begin{figure}[ht]
 \begin{subfigure}{\textwidth}
   \centering
\includegraphics[width=6cm]{example-image-A} 
\includegraphics[width=6cm]{example-image-B} 
\caption{}%Vacoas}
\label{fig:a}
\end{subfigure}
\begin{subfigure}{\textwidth}
\centering
 \includegraphics[width=6cm]{example-image-C} 
\includegraphics[width=6cm]{example-image-A} 
\caption{}%{Plaisance}
\label{fig:b} 
\end{subfigure}
\caption{Variation} 
\label{fig:wind_speed}
\end{figure}

\end{document}

enter image description here

Code

\documentclass{article}
\usepackage{graphicx}
\usepackage{subcaption}

\begin{document}

\begin{figure}[H]
\centering
   \begin{subfigure}{0.45\textwidth}
   \centering
   \includegraphics[width=\linewidth]{example-image-A}
   \caption{}
   \label{fig:f1} 
\end{subfigure}\quad
\begin{subfigure}{0.45\textwidth}
   \centering
   \includegraphics[width=\linewidth]{example-image-B}
   \caption{}
   \label{fig:f2}
\end{subfigure}
\centering
\caption{(a) Some text (b) Some text}

\end{figure}
\end{document}